| Fig. 1. Pen-tailed Tree-Shrew (Ptilocercus lowii). |
In Africa the tupaias are apparently represented by the jumping-shrews, or elephant-shrews (so called from their elongated muzzles), constituting the family Macroscelididae. From the Tupaiidae the members of this family are readily distinguished by the fact that the socket of the eye, in place of having a complete bony ring, is separated from the hinder part of the skull merely by a post-orbital process of the frontal bone, and also by the more or less marked elongation of the tarsus or lower portion of the hind-limb; another feature being the union of the lower ends of the tibia and fibula. As indicated by one of their names, the members of the group leap after the fashion of gerbils, or jerboas, and hence walk much more on their toes than the majority of the order. In the typical genus Macroscelides, which ranges all over Africa and has numerous specific representatives, the dental formula is i. 3⁄3, c. 1⁄1, p. 4⁄4, m. 2/(2 or 3), total 40 or 42; while there are five toes to each foot, and the lower ends of the radius and ulna are united. In Petrodromus (fig. 2) of East Africa, there are only four front-toes, and the hairs on the lower part of the tail form stiff bristles, with swollen tips; the dental formula being the same as that of those species of Macroscelides as have only two lower molars. A further reduction of the number of the digits takes place in the long-nosed jumping-shrews of the genus Rhynchocyon, which are larger animals with a much longer snout, only four toes to each foot, and a dental formula of i. (1 or 0)/3, c. 1⁄1, p. 4⁄4, m. 2⁄2, total 36 or 34. Some of the species, all of which are East African, differ from the members of the typical genus by the deep rufous brown instead of olive-grey colour of their coat. (See [Jumping-Shrew.])
In the second group, which includes all the other members of the order, the pelvic symphysis is either lacking or formed merely by the epiphyses of the pubes; the orbit and temporal region of the skull are confluent; and, except in the Talpidae and Chrysochloridae, the tympanum is ring-like, the tympanic cavity being formed by the alisphenoid and basisphenoid bones. The upper molars are triconodont, being either of the typical or a modified form of what is known as the tritubercular sectorial type. There is no caecum.
The first representatives of this group are the moles, or Talpidae, in which the lower ends of the tibia and fibula are united (fig. 3, t, fb), there is a descent of the testes, the tympanum forms a bladder-like bulla, the zygomatic, or cheek-arch, Moles. although slender, is complete, there is no pelvic symphysis, the upper molars are five-cusped, and the first upper incisor is simple, and the lower vertical. In habits the majority of the family are burrowing, but a few are aquatic; and all feed on animal substances. The distribution is limited to the temperate regions of Europe, Asia and North America.
Throughout the family the eyes are minute, and in some species are covered with skin; the ears are short and hidden in the fur; and the fore-limbs are generally more or less modified for digging.
| Fig. 2.—Peter’s Jumping-Shrew (Petrodromus tetradactylus). |
The true moles of the genus Talpa are the typical representatives of the first subfamily, or Talpinae, in which the clavicle (fig. 3, cl.) and humerus (h) are very short and broad, while there is an additional sickle-like bone (fc) on the inner side of the fore-foot. In Talpa itself the first upper incisor is but little larger than the second, the fore-foot is very broad, and the dental formula is i. 2⁄2, c. 1/(1 or 0), p. 3⁄3, 3⁄4, or 4⁄4, m. 3⁄3. There are about a dozen species, all confined to the Old World. The variation in the dental formula of some of the best known of these is as follows:—
| i. 3⁄3, c. 1⁄0, p. 4⁄4, m. 3⁄3 × 2 (T. wogura, robusta). i. 3⁄3, c. 1⁄1, p. 4⁄4, m. 3⁄3 × 2 (T. europaea, caeca, romana, longirostris, micrura). i. 3⁄3, c. 1⁄1, p. 3⁄4, m. 3⁄3 × 2 (T. leucura, leptura). i. 3⁄3, c. 1⁄1, p. 3⁄3, m. 3⁄3 × 2 (T. moschata). |
Except in T. europaea, the eyes are covered by a membrane. In T. micrura the short tail is concealed by the fur. T. europaea extends from England to Japan.
T. caeca and T. romana are found south of the Alps, the remaining species are all Asiatic, two only—T. micrura and T. leucura—occurring south of the Himalaya.