1893.] DR. C. J. rORSYTH MAJOR OX MIOCENE SQUIRRELS. 181 



cumstance is of ]io small iniportauco, as I shall have to point 

 out later on. 



The Common iSqiiinx'l, and iiiany Oriental members of the genns, 

 as well as some Ethiopian 8i|uirrels (Sc. rtifohrachiatas, AV^aterh., 

 aiDU'laius, Desm., sJitraisis, (Iray, jmnciaius, Temm.), .show rela- 

 tively prominent cusps, and present a transitional stage between 

 semi-hypsodontism and brac-liydontism. Still more brachydont are 

 two other groups A\hich have little affinity with each other — the 

 African .SV. stdiv/eri, AVaterh., So. ehii, Temm., aS'c. auhimiii, Gv., and 

 the Oriental (riant Squirrels {Sc. hkolor, mdicvs, riHicmrvs, etc.). 



The Oriental Pigmy Squirrels (Sc. cwil-is, Miill., Sc. mclanotis, 

 Miill. & Schl, .SV. con'chuius, Thos. (Plate X. fig. 10, Plate XI. 

 fig. 7), Sc. wJiiteJicadi, Tlios.), as well as the pigmy Ethiopian 

 Sc. viiiwfas, Du Chaillu (Plate XL fig. G), show a low, oval-shaped 

 and nearly horizontal crown, slightly conca\e in the middle, with 

 transverse ridges. On the \\liole, their dentition has scarcely any- 

 thing to do Anth the Sciuromorphous type of molars, and can only 

 be compared A^itli that of the Myoxidte, Eliomys and Grapli'mrus. 



Xext we have to consider the pattern of the molars in Sciurina'. 

 The numerous modifications — almost every species presents some 

 peculiarity — may be arranged under three heads : — 



1. The first type is represented by the most brachydont forms : 

 some Eocene Squirrels, as Sc. spcctahilis^ Maj., from Egerkingen, 

 the Borneau liliiihyosc'mrus (Plate IX. fig. 2), the Oriental Giant 

 Squirrels (Plates A'lII. and IX. fig. 1), the Ethiopian Sc. stangeri 

 (Plate A'lII. fig. 7, Plate IX. fig. 7) and its allies, Sc. ehii and 

 Sc. auhinnii (Plates A^III. and IX. fig. 8). 



2. The second type is represented by Sc. vul(/aris and its ally 

 Sc. syriacns (I have had no opportunity of examining thii dentition 

 of the Japanese Sc. Jis), by most of the Oriental middle-sized 

 Squirrels (Sc. precosti (Plate A'lII. fig. 2), Sc. lol-roides (Plates 

 A'lll. and IX. fig. 3), &c.), by a small Ethiopian group (Sc. 

 shirensis., Sc. aniiidatus, Sc. punctatvs, Sc. rvfohracliialvs), and by 

 most of the American Squirrels. 



3. The third type is represented by several groups of Ethiopian 

 Squirrels : Xerus (Plates A^III. and IX. fig. 10), including the 

 Moroccan X.r/etidvs (Plates A'lII. and JX. fig. 0), by Sc. cepapi 

 (Plate A^lll. fig. 22, Plate IX. fig. 23), Sc. paJliaius, Sc. pyrropxis 

 (Plate A'lll. figs. 15, 23, Plate IX. figs. 15, 22), Sc. com/icns, 

 Sc. Iciiiniscalus, Sc. Isabella (Plates A'JJI. and IX. fig. 24), Sc. 

 Jioehmii ; as well as by some Oriental forms, Sc. herdmorei (Plates 

 VIII. and IX. figs. 16-18), Gray's genus lihinoscianis (Plates 

 A^III. and IX. figs. 11, 12), &c. 



I do not consider for the present the African and Oriental 

 Pigmy Squirrels, as the charactei's of their dentil iou d(;part entirely 

 from the Sciuromorphan type as a whole. 



Brachydontism in itself is (piite generally admit led to be the 

 most generalized condition, and the feiith puiiit in the same* 

 direction as do those of other Orders, viz., towards a still more 

 primitive type. Besides, we are able to show that the two otlior 



