| OCR Text |
Show 92 MR. E. R. ALSTON ON THE GENUS ANOMALURUS. [Feb. 16, cervical 7, dorsal 16, lumbar 9, sacral 4, caudal 28 ; the latter much elongated. The posterior ridge of the scapula is very salient; and the humerus has a moderate deltoid ridge. The femur has a crest representing the third trochanter ; and the slender fibula is quite distinct from the tibia; in Pteromys these bones are often closely united below, though not truly fused. Dentition.-The grinding-teeth of the Anomalure are four in number on each side above and below, the small anterior premolar of Pteromys being absent; this tooth, however, is lost early in life in many species of Squirrel. Their series converge in front; and they are placed obliquely; so that the crowns of the upper teeth look outwards, and those of the lower jaw inwards. These crowns are worn perfectly flat even in young individuals, exposing islands of cement separated by cross folds of enamel, which are more directly transverse and less twisted than in the more complicated teeth of Pteromys. In the typical skull of A. beecrofti, in the British Museum, the cemental spaces are smaller and more isolated than in the other species. Viscera.-These, like the masticatory apparatus, differ much from those of the Sciuridce, and, indeed, present peculiarities not met with in any.other family of the order. Fig. 2. Cajcuin of A. fraseri, natural size. The tongue resembles that of the Squirrels, but is narrower and more pointed. The circumvallate papillae are two in number, and are placed transversely. The oesophagus has a short abdominal course after passing through the diaphragm, extending in A. fraseri to about half an inch ; its epithelium is not continued beyond the cardiac orifice. |
