Page:EB1911 - Volume 14.djvu/674

Rh above, the extremities of the hairs on the back being of a metallic violet hue by reflected light, beneath whitish.

In the remaining groups the upper molars form narrow V’s of the true tritubercular type. The family, Centetidae, represented by the tenrec and a number of allied animals from Madagascar, is specially characterized by the ring-like tympanic, and the absence of a zygomatic arch and of any constriction of the skull

behind the orbits, and the presence of teats on the breast as well as the abdomen. In the more typical members of the family the tibia and fibula are separate, and, as in hedgehogs, spines are mingled with the fur. The true or great tenrec (Centetes ecaudatus), alone representing the typical genus, has the dental formula i. $3 or 2⁄3$, c., p. , m. $3 or 4⁄3 or 4$, total 38, 40, 42 or 44. The fourth lower molar, when developed, does not appear till late in life. Of the long and sharp canines, the tips of the lower pair are received into pits in the upper jaw (fig. 9). The creature grows to a length of aoout a foot. The young have strong white spines arranged in longitudinal lines along the back, but these are lost in the adult which has only a crest of long rigid hairs on the nape of the neck. The lesser tenrecs, Hemicentetes semispinosus and H. nigriceps, are distinguished by the persistence of the third upper incisor and the form of the skull. The two species are much smaller than the great tenrec, and spines are retained in the adult on the body. The hedgehog-tenrec, Ericulus setosus, has the whole upper surface, and even the short tail, densely covered with close-set spines. The facial bones are much shorter than in the preceding genera, and the first upper incisors are elongated; while there are only two pairs of incisors in each jaw. Judging from the slight development of the cutaneous muscles compared with those of the hedgehog, it would seem that these creatures cannot roll themselves completely into balls in hedgehog-fashion. A second species of this genus, Ericulus (Echinops) telfairi, has two, in place of three, pairs of molars, thus reducing the total number of teeth to 32. Moreover, the zygomatic arches of the skull are reduced to mere threads. Here should perhaps be placed Geogale aurita, a small long-tailed Malagasy insectivore, with 34 teeth, and no spines; the tibia and fibula being separate. It has been classed in the Potamogalidae, but from its habitat such a reference is improbable. The absence of spines may entitle it to separation from the Centetinae, so that it should perhaps be regarded as representing a subfamily, Geogalinae, by itself.

The absence of spines coupled with the union of the tibia and fibula form the leading characteristics of the subfamily Oryzorictinae, typified by the rice-tenrecs Oryzorictes, of which there are several species. These creatures, which excavate burrows in the rice-fields of Madagascar, are somewhat mole-like in appearance, but have tails of considerable length. In the typical O. hova the fore-feet are five-toed, but in O. tetradactylus the number of front digits is reduced to four. The long-tailed tenrecs (Microgale) are represented by fully half-a-dozen species with tails of great length; that appendage in the typical M. longicaudata being more than double the length of the head and body, and containing no fewer than forty-seven vertebrae. The teeth are generally similar to those of Centetes, but are not spaced in front; their number being i., c. , p. , m., , total 40, or the same as in Oryzorictes. Finally, Limnogale mergulus, a creature about the size of a black rat, has webbed toes and a laterally compressed tail, evidently adapted for swimming. See.

All the foregoing are natives of Madagascar. It has been suggested however, that two remarkable West Indian insectivores, namely Solendon cubanus of Cuba (fig. 11) and S. paradoxus of Hayti, should be regarded as representing merely a subfamily of Centetidae. It is true that the main features

distinguishing these strange creatures from the Malagasy representatives of that family are the constriction of the skull behind the orbits, the descent of the testes into the perineum, and the post-inguinal position of the teats, and that none of these are of very great importance. But the geographical positions of the two groups are so widely sundered that it seems preferable to await further evidence before definitely assigning the two to a single family; and the family Solenodontidae may accordingly be retained for the West Indian animals. Solenodons, which look like huge long-nosed, parti-coloured rats, have the tibia and fibula separate, and the same dental formula as Microgale. Each of the two species (which differ in colour and the quality of the fur) has a long cylindrical snout, an elongated naked tail, feet formed for running, and the body clothed with long, coarse fur. The position of the teats on the buttocks is unique among Insectivora. The first upper incisors are much enlarged, and like the other incisors, canines and premolars, closely resemble the corresponding teeth of Myogale; the second lower incisors are much larger than the upper ones, and hollowed out on the inner side.

The last family, Chrysochloridae, is represented by the golden moles of South and East Africa, which differ from the Centetidae and Solenodontidae by the development of a bulla to the tympanic, and the presence of a zygomatic arch to the skull; the tibia and fibula being separate, and the symphysis

of the pelvis formed merely by ligament. The skull is not constricted across the orbits. The teats, which are placed both on the breast and in the groin, are situated in shallow depressions. The ears are buried in the fur, and the eyes concealed beneath the skin; the feet are four-toed and provided with powerful claws for burrowing