1893.] DR. C. J. FORSYTH MAJOR OX MIOCESE SQUIRRELS. 185 



shape of inferior molars tends to disappear. The species which 

 present in a greater or lesser degree this conformation are, besides 

 XtTvs (Plates YIII. and IX. fig. 10), including X f/etidns, Gesn. 

 (Plates Yin. and IX. fig. 9), Sc. palliaivs, Pet., Sc. cepapi, Smith 

 (Plate YIII. fig. 22, Plate IX. fig. 23), Sc. pi/rrojms, P. Cuv. 

 (Plate YIII. figs. 1.5, 23, Plate IX. figs. 15, 22), Sc. coni/kvs, Kuhl, 

 Sc. leninisi'atvs, Le Conte, Sc. isahi'lla, Gr. (Plates YIII. and IX. 

 fig. 24), and >SV. hwhtnl, Eeich. At the same time they present in 

 their skull some resemblance to the Ilystricomorpha. They also 

 approach Aiiomahinis (Plato?; YIII. and IX, figs. 13, 14), the 

 various hystricomorphine i-haracters of u hich have long ago been 

 noted, but ha'w, I think, rather been underrated by Alston \ 



It thus would appear that we ha^•e here a group of Sciuromorpha, 

 some^^'hat specialized in the direction of Hystricomorpha, as we 

 find, too, in several Eocene Eodentia. 



But this is not all. The molars of Sc. berdmorei, Bly. (Plates 

 YIII. and IX. figs. IG-IS), an Oriental Squirrel, and those of the 

 Borueau '• JiJtiaoscuirus, Gr." (Plates YIII. and IX. figs. 11, 12), 

 agree with those of A^cj^^and the above-named Ethiopian. Squirrels, 

 not only in their semi-bypsodontism, but likew ise in their lopho- 

 dontism, whilst the less semi-hypsodont Oriental Sc. iristriatns, 

 "NYaterh., and Sc. palm a run}, L., tend to connect the Xevns-t\\)e with 

 the Sc.-viih/aris-tji^e, in approaching the form of molar of most 

 of the " middle-sized " Oriental Squirrels. Two other Oi'iental 

 species, Sc. i7isiffms, F. Cuv. (Plates A^III. and IX. fig. 6), and 

 Sc. Jiosei, Thos.^ (Plates YIII. and IX. fig. 5), from Borneo, 

 though semi-hypsodont, and in other characters agreeing with 

 the members of the A>/'i/.$-group, show a remarkable modification 

 in the pattern of the molars, the valleys being reduced to mere 

 su]K^rficial cracks, which di3api)ear very early by wear. I thiuk 

 that we have in the molars of these two forms examples of that 

 kind of retrogressive evolution of the molars to which attention 

 has been lately drawn in an important paper by Leche ^ who 

 attributes it to the modification of food. The Jlncroi/hssi, Picrojins 

 scapulafus, and the Ejiomojihon., differing in this respect from 

 other Pterojil, feed on juicy fruits, whose contents need not be 

 eliewcd. Likewise Chiromi/s madaijascarieiisia, the molars of 

 uliich ]n'esejit a similar kind of retrogressive evolution, is known 

 to feed principally on succulent juices, especially of the sugar- 

 cane, as well as on wood-boring caterpillai's. It now is very 

 suggestive that /S'n »/>•/'•-} i/m//»i>, according to Miiller and Schlegel', 

 is especially fond of juicy and aromatic fruits of dilferent species 



' Edward R. Alston, "On .iininui/iirns, itn sti-iictui-o and position" (Proc. 

 Zool. Soc. IST.'i, p. 04). 



- Ann. Mag. Nat. Hist, for Sept. 180l', pp. 21."), 210. 



' W. Tjcclie, " Stndien iibor die J'^nlwipkliing des Zahii8ystenm hci diii 

 Siingethieren," Morphuhig. .Talirbiifli, \ix. I'^'.l^, pp. .'')4.'3, .'')44. 



' Sal. Miiller &. Herni. .Sclilcpel, " (~)v('r de tul liedcn bekendo Kekhurens 

 {Sciiiriin) van den Indiselien Arcliipel," "W-rliandolingen over de Nalnrlijke 

 GeschiedenlR der Nederlandselic over/.eeBciie Bezittingen," Leiden, ]8.'30-44, 

 p. W. 



