694 CLASS xvii. 



Temm. These species from the West coast of tropical Africa deviate from 

 all the Sclurlna 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. Gervais Description 

 osteol. de I'Anomalurus et remarques siir la classification naturelle des 

 Rongeurs, Ann. des So. nat., ^me S^rie, xx. 1853, pp. 238 — 246, PI. 13, 

 fig. 1—7. 



5 — 5 

 Pteyomys C\]Y., Geoffe., Illio, Molar teeth j — j, tlie first 



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 ; fibro-carti- 



laginous falciform support inserted in the carpus at tlie outside. 



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



. 1-1 2-2 3-3 _. 



^•rri'PT=l' ^^-333 = 22.) 



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

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



Sp. Pteromys j)etam'ista, Sciurus iMaurista Pall. Misc. Zool. Tab. vi. Vos- 

 MAER Beschrijving van den grooten Oost- Indischen vliegenden eekhoorn, 

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

 and the following sub-genus the infra-orbital foramen is very smal^) 



Sciuroj)terus F. Cuv. Molar teeth tuberculate. Tail shorter 

 than body, flat, distichous. 



Sp. Pteromys vuli/aris Wagn., Sciurus volansh. (excl. syn. Catesb.), Schreb. 

 Sdugth. Tab. 223, Blumenb. Ahhild. nat. Gegenst. No. 71; in the North- 

 east of Europe and Siberia ; — Pteromys volucella, Sciurus volucclla Gm., 

 BaFP. X. PI. 21, GUERIN Iconof/r., Mammif. PI. 23, fig. 3, Did, univ. 

 d'llist. nat., 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 



J — 2 ) tuberculate, marked by exsert transverse strice, enamelled 



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

 Fore feet tetradactylous with liallucar wart unguiculate. Claws 

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



