1893.] DR. C. J. rOKSXTH MA JOE, OS MIOCEliTE SQtriREELS. 181 



cumstance is of no small importance, as I shall have to point 

 out later on. 



The Common Squirrel, and many Oriental members of the genus, 

 as well as some Ethiopian Squirrels (So. rufobrachiafus, Waterh., 

 aamdatus, Desm., sJiiroisis, O-ray, punctatus, Temn).), show rela- 

 tively prominent cusps, and ]iresent a transitional stage between 

 somi-hypsodontism and brachydontism. Still more brachydont are 

 two other groups which have little affinity with each other — the 

 African /S'c. sfmu/eri, AVaterh., Sc. ehii, Temm., Se. auhinnii, Gr., aiifl 

 the Oriental Giant Squirrels (Sc. hkolor, inclims, mncnmts, &c. ). 



The Oriental Pigmy Squirrels {Sc. eailis, Miill., Sc. melnnolis, 

 Miill. & Schl., Sc. concimins, Thos. (Plate X. fig. 10, Plate XI. 

 fig. 7), Sc. H'Jiiteheadi, Thos.), as well as the pigmy Ethiopian 

 Sc. minutus, Du Chaillu (Plate XI. fig. 6), show a low, oval-shaped 

 and nearly horizontal crown, slightly concave in the middle, with 

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

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

 be compared witli that of the Myoxidte, Eliomys and Graplmirus. 



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

 The numerous modifications — almost every species pi-esents some 

 peculiarity — may be ari'anged under three heads : — 



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

 some Eocene Squirrels, as Sc. spectuhUis, Map, from Egerkingen, 

 the Bornean liJiifhroschn-us (Plate IX. fig. 2), the Oriental Giant 

 Squirrels (Plates VIII. and IX. fig. 1), the Ethiopian Sc. slangeri 

 (Plate VIII. fig. 7, Plate IX. fig. 7) and its allies, Sc. ehii and 

 Sc. auhinnii (Plates VIII. and IX. fig. 8). 



2. The second type is represented by Se. vulgaris and its ally 

 Sc. syriacus (1 have had no opportunity of examining the dentition 

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

 Squirrels {Sc. lyrerosti (Plate A'lII. fig. 2), Sc. Jol-roides (Plates 

 VIII. and IX. fig. 3), &c.), by a small Ethiopian group {Sc. 

 shirensis, Sc. anmdatus, Sc. punctattis, Sc. nifobrachiatns), and by 

 most of the American Squirrels. 



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

 Squirrels : Xenis (Plates VIII. and IX. fig. lU), including the 

 Moroccan A', qettdus (Plates VIII. and IX. fig. 9), by Sc. cepapi 

 (Plate A^III. fig. 22, Plate IX. fig. 23), Sc. palUatus, Sc. p>yr)-opii,s 

 (Plate VIII. figs. 15, 23, Plate IX. figs. 15, 22), Sc. conyicns, 

 Sc. lemniscatus, Sc. isahella (Plates VIII. and IX. fig. 24), Sc. 

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

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

 VIII. and IX. figs. 11, 12), &c. 



I do not consider for the present the African and Oriental 

 Pigmy Squirrels, as the characters of their dentition depart entirely 

 from the Sciuromorphan type as a whole. 



Brachydontism in itself is quite generally admitted to be the 

 most generalized condition, and tlie teeth point 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 other 



