54 Zoological Society. 



opposite sides of the jaw are parallel, and the ant-orhital opening is 

 small, in the form of a tuhe, and serves only for the transmission of 

 the infra-orbital nerve. These characters are not found in Anoma- 

 lurus : the post-orbital process is here reduced to a mere rudiment, 

 being represented by an indistinct projection forming an obtuse 

 angle : the ant-orbital opening is large, and evidently affords a pas- 

 sage for a portion of the masseter muscle as well as the nerve ; it 

 moreover opens directly in the bony plate which constitutes the an- 

 terior root of the zygomatic arch, and is not produced as it were into 

 a tube, as in the typical Squirrels. The palate is narrow, and has a 

 deep triangular emargination behind, the apex of the triangle being 

 on a line with the hinder margin of the penultimate molar. The 

 molar teeth converge in front, so that the space between the two 

 foremost is scarcely equal in width to one of these teeth ; the crowns 

 of the molars of opposite sides of the upper jaw, instead of being on 

 the same plane, or very nearly so, are directed obliquely outwards ; 

 and the masticating surface of those of the lower jaw, to meet them, 

 incline in an opposite direction. The incisive foramina are longer 

 than is usual in the Sciuridce, and encroach in a slight degree upon 

 the maxillary bones. The nasal portion of the skull is narrower, and 

 the nasal bones are remarkable for a deep emargination in front. 



I have been led to institute a comparison between the present 

 animal and the species of the Sciurida, on account of certain points 

 of resemblance which there exist between it and the Flying Squir- 

 rels {Pteromijs), especially in the possession of the expanded flank 

 and interfemoral membranes. In the almost total absence of post- 

 orbital process, however, and in the comparatively large size of the 

 ant-orbital opening, the Anomalurus evinces an approach to the 

 Myoxidce ; the approximation is moreover observable in the narroM^- 

 ness of the nasal bones and the slenderness of the zygomatic arch, 

 these parts being compared with those corresponding in the squirrel 

 sknll. 



The lower jaw is formed like that of the Squirrels, and does not 

 present certain peculiarities observable in the Myoxus, viz. that of 

 having the descending ramus perforated, its posterior angle acute, 

 and the upper posterior angle produced. 



The incisor teeth are deeper than broad, and almost flat in front. 



4 4 



The molars are permanently, it would appear, 737. for in a skull of 



a young animal in which but three molars on either side of the jaw 

 are protruded, there is no trace of the small anterior molar so com- 

 monly found in the Squirrels. They are very nearly equal in size, 

 and of a quadrate form ; the crown of each molar of the upper jaw 

 is slightly indented, both on the outer and inner side, and the poste- 

 rior inner angle is somewhat produced ; in the young animal it is 

 more distinctly produced and is acute, and the outer and inner in- 

 dentations are scarcely traceable. The molars of the lower jaw have 

 each a strong indentation on the outer side. The folds of enamel 

 cross the crowns of the molars in the transverse direction, and the 

 spaces between the folds (four or three in number) are about equal 



