Sub-Order 1. Insectivora Vera

Fam. 1. Erinaceidae.—This family contains the genera Erinaceus, Hylomys, and Gymnura.

Hylomys, considered by Dobson to fall within Gymnura, is kept separate by Leche. H. suillus is a Malayan animal, small in size, about 5 inches long, with a short tail. Like Gymnura it is spineless. The ears are decidedly large and nude. There is one pair of inguinal and one pair of thoracic teats. The colour above is a rusty brown with yellowish-white under parts. The palms and soles are quite naked. In its general form it recalls Tupaia very much more than its own immediate relatives. There is no doubt, however, of its systematic position when the skeleton and teeth are examined. A variety has been described from altitudes of 3000 to 8000 feet on Mount Kina Balu in Borneo. It has the complete dentition of forty-four teeth. There are fourteen pairs of ribs. As in Gymnura the tibia and fibula are united below. The genus is considered by Leche to be the oldest existing type of Erinaceidae.

Gymnura is also a Malayan form with the complete dentition of the last, but with fifteen pairs of ribs and a longer tail, consisting of twenty-three vertebrae as against fourteen. There is, as with Hylomys, but one species, G. rafflesii. This animal has a peculiar odour, resembling decomposed cooked vegetables. The under surface of the tail is rough, and it is thought by Dr. Blanford that it may be of use to the animal in climbing. Its compressed terminal third and the fringe of stiff bristles on the under surface of this indicate, according to Dr. Dobson, powers of swimming, or at any rate a not very remote ancestry of swimming creatures. It is purely insectivorous in diet.

Erinaceus, including the Hedgehogs, is a widely distributed genus—Palaearctic, Oriental, and Ethiopian in range. There are about twenty species. The familiar spines distinguish the Hedgehogs from their allies, as also the fact that they possess but thirty-six teeth, the formula being I 3/2 C 1/1 Pm 3/2 M 3/3. There are fifteen or fourteen ribs, and the tail is very short, consisting of only twelve vertebrae. As in Gymnura there is no caecum. The upper canine has usually, as in other Erinaceidae, two roots, but not in E. europaeus, which is one of the most modified of Hedgehogs.

The Hedgehog is a more omnivorous creature than Gymnura. It eats not only insects and slugs, but also chickens and young game birds, and lastly vipers. Four, or in some cases as many as five or six, young are produced at a birth; they are blind, with soft and flexible white spines. In hot and dry weather Hedgehogs disappear; they come forth in rainy weather. The English Hedgehog, as is well known, hibernates. The Indian species do not. The Hedgehog is occasionally spineless, which condition may be regarded as an atavistic reversion.

The Hedgehog has acquired the reputation of carrying off apples transfixed upon its spines. Blumenbach thus quaintly describes this and other habits of the animal, whose English name he gives as "hedgidog": "Il se nourrit des productions des deux règnes organisés, miaule comme un chat, et peut avaler une quantité énorme de mouches cantharides. Il est certain qu'il pique les fruits avec les épines de son dos, et les porte ainsi dans son terrier."

The Miocene Palaeoerinaceus is so little different from Erinaceus that it is really hardly generically separable. Erinaceus is therefore clearly one of the oldest living genera of mammals.

Necrogymnura of the same epoch and the same beds (Quercy Phosphorites) is doubtless an ancestral form. The palate is perforated as in Erinaceus (it is not so in Gymnura and Hylomys), but on the whole it comes nearest to Hylomys.

Fam. 2. Tupaiidae.—This family contains the genera Tupaia and Ptilocercus. Tupaia is Oriental in range, extending as far east as Borneo. There are a dozen or so of species, which are generally arboreal and have the outward aspect of Squirrels. It has been suggested that this is a case of mimicry, the animal gaining some advantage by its likeness to the Rodent. The name Tupaia, it should be added, means Squirrel, and the long-nosed Squirrel, Sciurus laticaudatus, is so extraordinarily like it that "one has to look at the teeth" to distinguish them. Moreover this Squirrel, like some Tupaias, lives largely on the ground among fallen logs. Tupaia resembles a Lemur in the complete orbit. The dental formula is I 2/3 C 1/1 Pm 3/3 M 3/3 = 38. The sublingua, too, is stated by Garrod to be like that of Chiromys. There is a minute caecum in T. belangeri, none in T. tana.

Ptilocercus has a pen-like posterior portion to the tail, a modification which is found in other groups of animals. The tail of certain Phalangers, for instance, shows this same modification. The rest of the tail is scaly. The animal, as was pointed out by Dr. Gray, looks very much like a Phalanger. The orbit is entire as in Tupaia. The fingers and toes are five. The one species, called after Sir Hugh Low, G.C.M.G., P. lowi, is a Bornean animal.

Fam. 3. Centetidae.—This family is entirely confined to the Island of Madagascar. It includes some seven genera. The best-known genus is Centetes. C. ecaudatus, the Tanrec, Tenrec, or Tendrac, is an animal a foot or so in length, without a tail, and with forty-four teeth. The immature animal is so different from the parent as to appear quite a different form. It has three narrow rows of spines along the back, which do not wholly disappear until the permanent dentition has been acquired. Even then the hairs are of a rather spiny character, particularly those upon the back of the head, which are erected when the animal is annoyed. The Tanrec feeds mainly upon earthworms. It is "probably the most prolific of all animals," since as many as twenty-one young are said to have been brought forth at a birth. Some Opossums, however, have twenty-five teats.

Fig. 248.—Skull of Tenrec. Centetes ecaudatus. fr, Frontal; max, maxilla; pa, parietal; p.max, premaxilla; sq, squamosal. (After Dobson.)

Hemicentetes is a genus with two species. These have spines mixed with the fur of the back. There is no caecum in this or in other Centetidae. The teeth are forty in number, there being only three molars.

Ericulus setosus is a small Insectivore, resembling externally a small Hedgehog. It is covered with close-set spines which, unlike what is found in Erinaceus, extend over the short tail. The total number of teeth is thirty-six, the formula being I 2/2 C 1/1 Pm 3/3 M 3/3.

Echinops is another spiny genus which is a stage in advance of Ericulus, for still another molar has been lost, reducing the total number of teeth to thirty-two. The dental formula is thus I 2/2 C 1/1 Pm 3/3 M 2/2. The zygomata are reduced to mere threads.

Microgale, a genus recently instituted by Mr. Thomas, is a small furry Insectivore with a long tail, which is more than double the length of the head and body. There are no less than forty-seven vertebrae in the tail, which is relatively longer than that of any other mammal.

Limnogale, discovered by Forsyth Major, is an aquatic genus, also furry and not spiny, which has departed from the Centetid type and taken to an aquatic life. The single species, L. mergulus, is about the size of Mus rattus; it has webbed toes and a powerful laterally-compressed tail. Clavicles are present, which is not the case with Potamogale.

Oryzoryctes is a Mole-like Centetid. It has fossorial fore-limbs, but a fairly long tail. This genus is furry like the last two. It is said to burrow in the rice-fields and to do much harm. The teeth are forty in number, three incisors and three molars in each half of each jaw.

Fam. 4. Potamogalidae.—This family contains two genera, Potamogale and Geogale.

Potamogale velox is a West African animal, which though an Insectivore has the habits of an Otter. It is "somewhat larger than a stoat." The upper surface of the body is dark brown, the belly brownish yellow. It has a flat head and a long tail like the Stoat, but the tail is laterally compressed and very thick. The eyes are very small; the nostril has valves. The toes are not webbed; but the second and third toes are united for the whole length of their first phalanges. Along the outer side of the foot is a thin extension of the integument. In swimming the feet are drawn up along the body, hence webbing would be of no use; but the thin flattening prevents the edge of the foot from acting as a hindrance to the motion of the animal. M. du Chaillu describes it as catching fish, which it pursues with extreme rapidity in the clear mountain streams it frequents; but Dr. Dobson, remarking that no stomachs have been examined, thinks that water insects are more probably its prey. It is not known whether the animal possesses a caecum. The tooth formula is I 3/3 C 1/1 Pm 3/3 M 3/3. The animal is exceptional among the Insectivora in having no clavicles. There are sixteen ribs; there is no zygomatic arch, and the pterygoids converge posteriorly.

Geogale, with one species, G. aurita, is a small representative of this family from Madagascar. It has only thirty-four teeth. When better known it may be necessary, thinks Mr. Lydekker, to make this animal the type of a separate family. The tibia and fibula are distinct, not confluent with one another as in Potamogale.

Fam. 5. Solenodontidae.—This family contains but a single genus.

Solenodon. This genus, including two species, one from Cuba, the other from Hayti, was at one time referred to the Centetidae. It offers, however, numerous points of difference from the members of that family with some general points of agreement. Possibly its isolation in the two West Indian islands mentioned is comparable to the isolation of the Centetidae in Madagascar; they are both survivors of an ancient group of Insectivores extinct elsewhere. Solenodon has nearly the complete dentition. It has lost only one premolar, and has therefore forty teeth in all. The formula is thus I 3/3 C 1/1 Pm 3/3 M 3/3. It also differs from the Centetidae in having only two inguinal mammae instead of both inguinal and thoracic; the penis of the male does not project from a cloaca, but lies forward. On the other hand, the molars have their cusps arranged in the V-fashion of the Centetidae, a fact, however, which, in the opinion of some, merely points to an ancient trituberculism not indicative of special affinity. It has, moreover, no zygoma in the skull, and there is no caecum. Dr. Dobson has furthermore tabulated a number of differences in muscular anatomy between the two families. Solenodon has a long naked tail. The snout, always developed in Insectivores, is extraordinarily long in this genus. It is a furry, not a spiny animal. S. cubanus is liable to fits of rage when irritated, a feature which it has in common with Shrews and Moles; it is also stated to have the ostrich-like way of concealing its head in a crevice, "apparently thinking itself then secure." But nothing is known of the genus in a wild state.

Fam. 6. Chrysochloridae.—This family contains only the genus Chrysochloris, comprising some five species, all natives of Africa south of the equator. The scientific name of the genus, and also the vernacular name Cape Golden Mole, are derived from the beautiful iridescent hairs which are intermingled with softer and non-iridescent fur. Chrysochloris has V-shaped cusped teeth like those that are possessed by the Centetidae and Solenodontidae. In the skull as in the Macroscelidae, etc., but not in the Centetidae, there are complete zygomata. They are Moles in habit, and the eyes are covered with skin; the ears, moreover, have no conches. The teeth are forty or thirty-six in number, the reduction being caused by the losing of a molar in those forms which possess the smaller number. It is interesting to notice that the adaptation to a digging life is brought about in quite a different way from that of the true Moles (Talpa). In the latter the fore-limbs are changed in position by the elongation of the manubrium sterni, carrying with it the clavicles, which are extraordinarily shortened (Fig. 251). In Chrysochloris, on the other hand, the same need (i.e. that the limbs project as little as possible from the sides of the body, while the length of the limbs is retained, and the leverage of the muscles unaffected) is provided for by a hollowing out of the walls of the thorax, the ribs and the sternum being here convex inwards. The sternum and the clavicles are not modified. The tibia and fibula are ankylosed below. In the manus, moreover, there are but four digits, of which the two middle ones are greatly enlarged. In the Moles there are five fingers, and all are enlarged; there is, too, a great radial sesamoid bone, which is as good as a sixth finger (which, indeed, it is considered to be, in common with similar structures in other animals, by some anatomists). The foot has only four toes.

Fig. 249.—Golden Mole. Chrysochloris trevelyani. A, Lower surface of fore-foot. × ½. (After Günther.)

Fam. 7. Macroscelidae.—This family contains three genera, all of them African in range, and mainly Ethiopian.

Macroscelides, the Elephant Shrews, are jumping creatures of Shrew-like appearance, combined with a Marsupial look. Both radius and ulna, and tibia and fibula, are ankylosed. There are five fingers and toes. There is a caecum as in but few Insectivores. The tooth formula, as revised by Thomas, is I 3/3 C 1/1 Pm 4/4 M 2/(2 or 3), the total number being thus forty or forty-two. There are several species of this genus.

Fig. 250.—Rhynchocyon chrysopygus. × ¼. (After Günther.)

Rhynchocyon and Petrodromus differ from Macroscelides in not having such long hind-legs. The dental formula of the first is I (1 or 0)/3 C 1/1 Pm 4/4 M 2/2 = 34 or 36, of the latter I 3/3 C 1/1 Pm 4/4 M 2/2 = 40. In Petrodromus the toes are reduced to four; in Rhynchocyon there are only four digits in the manus as well as in the pes. This animal, as its name implies, has a longish proboscis, which can be bent, and is really very like a miniature Elephant's trunk, and also like that of the Desman (Myogale). It has thirteen pairs of ribs, and a well-developed caecum. Dr. Günther has pointed out that in Petrodromus tetradactylus the hairs of the lower part of the tail are stiff elastic bristles 5 mm. long, with a swelling at the free tip. The use of this singular modification is not at all apparent. Pseudorhynchocyon, of European Oligocene, is believed to be related to this family.

Fig. 251.—Sternum and sternal ribs of the Common Mole (Talpa europaea), with the clavicles (cl) and humeri (H); M, Manubrium sterni. Nat. size. (From Flower's Osteology.)

Fig. 252.—Bones of fore-arm and manus of Mole (Talpa europaea). × 2. C, Cuneiform; ce, centrale; l, lunar; m, magnum; p, pisiform; R, radius; rs, radial sesamoid (falciform); s, scaphoid; td, trapezoid; tm, trapezium; U, ulna; u, unciform; I-V, the digits. (From Flower's Osteology.)

Fam. 8. Talpidae.—This family is confined to the Palaearctic and Nearctic regions, or practically so, being fairly equally distributed as regards genera; a Mole just gets over the boundary into the Oriental region. The genus Talpa is entirely Old World in range, and includes several species, of which the Common Mole, T. europaea, is the best known. There are forty teeth, one of the molars of the full mammalian dentition not being represented. In the milk dentition there is an additional premolar, not represented by a successor in the permanent dentition. The formula is thus I 3/3 C 1/1 Pm 4/4 M 3/3. There are no external ears, and the eyes are rudimentary; the soft silky fur is familiar to everybody. The sternum has a strong crest, associated with a powerful development of the pectoral muscles, so necessary to a burrowing animal. The animal, it is hardly necessary to state, lives underground in burrows excavated by itself, which have not, it has been stated, the elaborate and, it appears, fanciful shape assigned to them by many writers. At times Moles appear above ground. Their principal food consists of earthworms, and it may not be out of place to quote Topsell's quaint account of their pursuit of the annelids: "When the wormes are followed by molds (for by digging and heaving they foreknow their owne perdition) they fly to the superficies and very toppe of the earth, the silly beast knowing that the molde, their adversary, dare not followe them into the light, so that their wit in flying their enemy is greater than in turning againe when they are troade upon." It has lately been said that Moles store up earthworms for consumption during the winter, biting off their heads to prevent their crawling away.

Scalops, an American genus, is a Mole-like creature of largely aquatic habits, as its webbed hind-feet show; it has a short, naked tail. Apparently, like the Shrews, it has no lower canines.

Condylura, another American genus, is called the Star-nosed Mole on account of a curious radiating structure at the end of the snout.

Myogale, the Desman, is still more aquatic in habit, and connects the Moles with the Shrews, though, as in many of the former, it has lower canines. It has webbed hind-feet and a long tail. One species occurs in the Pyrenees, the other in Russia. A few other genera (Urotrichus, Uropsilus, Scaptonyx, Dymecodon, Scapasius, Perascalops) belong to the same family.

Fam. 9. Soricidae.—The true Shrews have a much wider range than other families of the present order. In the Palaearctic region are found Sorex, Crossopus, Crocidura, Nectogale, Chimarrogale. The first is also Nearctic, and reaches Central America. In the Ethiopian region is the single peculiar genus Myosorex, but Crocidura occurs there also. Blarina and Notiosorex are "Sonoran" in range; Soriculus Oriental. Crocidura, Anurosorex, and Chimarrogale also enter this region. Sorex has teeth tipped with reddish colour, its dental formula being, according to Mr. Woodward's recent researches, I 3/(2 or 3) C 1/0 Pm 3/1 M 3/3 = 32 or 34.

As compared with other Insectivores, therefore, the most remarkable fact found throughout the family is the absence of the lower canines. In addition to this the genus may be known—the family indeed—by the large size of the first pair of incisors. In the above formula it is possible, thinks Mr. Woodward, that there may be errors; he is not certain whether the supposed upper canine may not be a fourth incisor, and whether the first premolar may not be really the canine. Another peculiar feature about the dentition of Sorex is the suppression of the teeth of the milk dentition, which are functionless, and probably uncalcified. The genus Sorex is terrestrial. The tail is long and covered with hairs. There are two species in this country, S. vulgaris and S. minutus. The former is the Shrew of legend and superstition; and it is no doubt the species that has lent its name to the more untameable members of the softer sex, though it is the males which are especially pugnacious. As to legend, everybody has heard of the shrew ash whose leaves, after a Shrew has been inserted living into a hole cleft in the tree, are a specific for diseases of cattle, caused by the Shrew itself creeping over them.

The Rev. Edward Topsell, author of The Historie of Four-footed Beastes, who defends his veracity by asserting that he does not write "for the rude and vulgar sort, who being utterly ignorant of the operation of learning, do presently condemne al strange things," says of the Shrew that "it is a ravening beast, feigning itself gentle and tame, but, being touched, it biteth deep and poysoneth deadly. It beareth a cruel minde, desiring to hurt anything, neither is there any creature that it loveth, or it loveth him, because it is feared of all." It is probable that all this rustic feeling is due to the powerful effluvium which the Shrew undoubtedly emits.

S. minutus has the distinction of being the smallest British mammal; it is scarcer than the last. This form is found upon the Alps, as is also the peculiarly Alpine species S. alpinus, which inhabits the Alps, Pyrenees, Carpathians, and the Hartz.

Crossopus fodiens, the Water Shrew, has also brown-stained teeth. It is not uncommon in this country, and lives in burrows excavated by the sides of the streams which it affects.

Besides these two genera, Soriculus, Blarina, and Notiosorex have red-tipped teeth. In Crocidura, Myosorex, Diplomesodon, Anurosorex, Chimarrogale, and Nectogale the teeth are white-tipped. These are all the genera of the family allowed by the late Dr. Dobson in a review of that family.

Chimarrogale and Nectogale are aquatic genera. The former consists of a Himalayan and Bornean, and of a Japanese species, which have not webbed feet, but have a tail with a fringe of elongated hairs.

Nectogale elegans is one of the characteristic animals of the Thibetan plateau. It has webbed feet. The teeth are as in Chimarrogale I 3/2 C 1/0 Pm 1/1 M 3/3.

The other genera are terrestrial in habit.