Generic Arrangement of the African Squirrels. 409 



b*. Cheek-teeth * 2. Heliosciurus. 



b". Skull high, forehead level. Anteorbital foramen above^. 



Cheek-teeth ? 3. Myrsilus. 



b^. Lower molars more or less ridged transversely. Teeth ^• 

 c^. Lower molars regularly and deeply ridged, without high 



cusps. Muzzle very long 4. Funisciurus. 



d^. Lower molars irregularly ridged, with high cusps. Muzzle 

 not specially elongated 5. Paraxeriis. 



b. Size very large, skull-leugth exceeding 64 mm. ; zygoma-root 



bowed over as in Xerus, its front edge suipassing the maxillo- 

 premaxillarv suture. Cheek-teeth -. 



c^. Skull normal. Muzzle short ; bullae large ; anteorbital 



foramen rounded 6. Protnxerus. 



(P. Skull elongate. Muzzle long ; bullae small ; anteorbital 



foramen slit-like 7. Ejnxerus. 



B, Fur spinous. Palate produced in middle line some way behind 

 molars. Ridge of zygoma-root strongly bowed forwards. Post- 

 orbital processes directed backwards, near the hinder end of the 

 combined orbi to-temporal fossae. 



c. Brachyodont, or very slightly hypsodout. (Size smaller, skull- 



length below 5o mm.) 



c^. Cheek-teeth -. Skull flattened 8. Atlcmtoxerus, 



P. Cheek-teeth 1 Skull more arched 9. Xerus. 



J 4 



d. Strongly hypsodont. (Length of skull above 55 mm.) 

 g^. Cheek-teeth j. Skull arched, broad aud heavy. 



10. Geosciurus. 

 h^. Cheek-teeth -. Skull high, narrow 11. Euxerus. 



n. Size minute, skull-length about 25 mm. Skull highly abnormal: 

 anterior zygomatic plate vertical ; postorbital processes minute ; 

 orbits occupying practically the whole of the orbito-temporal fossae. 

 (Nannosciurinae.) 



e. Cheek-teeth i. Ectopterygoid suppressed. .. . 12. Myoscittrus. 



1. SCIURUS. „ 



Type. 



Linn. Syst. Nat. (10) i. p. 63 (1758) S. vulgaris. 



Three African species, with distinctly basin-shaped lower 



molars and - cheek-teeth, maj be provisionally referred to 



Sciurus. They are not very uniform among themselves in 

 their skull-shapes, nor is any one of them closely similar to 

 S. vulgaris^ but the many forms of Sciurus found in the East 

 present so great a range of variation that no tangible or 

 constant characters can be found to separate off these African 

 species. 



The three are S. poensiSj Smith, lucifer, Thos., and 

 rmvenzorii y^ohwMWx. 



