694 G'LASS XVII. 



TEMM. Tliese species from the West coast of tropical Africa deviate from 

 all the Sciurina in the absence of the post-orbital process of the frontal 

 bone, in the large infra-orbital foramen and in the large number of ribs 

 (15 pairs, whilst the rest of the Sciurina have only 12, except very few 

 which have 13). The skull has a convex surface above the orbits, as in 

 Arctomys. A cartilaginous, falciform ligament for the support of the 

 parachute passes off from the ulnar process. P. GEBVAIS Description 

 osteol. de VAnomalurus et remarques sur la classification naturelle des 

 Rongeurs, Ann. des Sc. nat., 3tne Se'rie, xx. 1853, PP- 2 3^ 246, PL 13, 

 fig. i-7- 



PJ _ ^ 



Pteromys Cuv., GEOFFR., ILLIG. Molar teeth ^ -: , the first 



4 4 



upper very small, placed at the inside of the second. Feet as in 

 the preceding genus. Hairy skin at the sides of body produced 

 between the fore and hind feet, rising from the carpus ; fibre-carti- 

 laginous falciform support inserted in the carpus at the outside. 

 Tail covered with hair below and above. (Dent. form. OWEN, 

 . 1-1 2-2 3-3 . 



Pteromys (in stricter sense). Molar teeth complex. Tail rounded, 

 densely haired, of the length of body or longer than body. 



Sp. Pteromys petaurista, Sciurus petaurista PALL. Misc. Zool. Tab. vi. Vos- 

 MAEB Beschrijving van den grooten Oost- Indischen vliegenden eekhoom, 

 Amsterdam, 1767, 4to (with col. fig.); Pteromys nitidus, &c. (In this 

 and the following sub-genus the infra-orbital foramen is very small.) 



Sciuroptei-us F. Cuv. Molar teeth tuberculate. Tail shorter 

 than body, flat, distichous. 



Sp. Pteromys vulyaris WAGN., Sciurus volans~L. (excl. syn. CATESB.), SCHREB. 

 Sdugth. Tab. 223, BLUMENB. Abbild. nat. Gegenst. No. 71; in the North- 

 east of Europe and Siberia ; Pteromys volucella, Sciurus volucella GM., 

 BUFF. x. PI. 21, GUERIN Iconogr., Mammif. PI. 23, fig. 3, I>ict. univ. 

 d'Hist. not., Mammif. PI. 9 A ; North America, &c. 



Sciurus L. (excl. some spec.). Incisor teeth smooth in front, 

 brown or orange-coloured, the lower compressed, acute; molars 



5 5 



A_A 5 tuberculate, marked by exsert transverse striae, enamelled 



continuously, with first small and placed at the inside of second. 

 Fore feet tetradactylous with hallucar wart unguiculate. Claws 

 compressed, incurved. Skin not expanded at the sides of body. 



