1200 MR, K. I. POCOCK ON THE EXTERNAL CHARACTERS 



middle of the metatarsal surface nearly or quite up to the level 

 of the hallucal lobe. (Text-fig. 54, B, D.) 



The feet of Mm^tnota marmota are relatively moi'o robust and 

 somewhat shorter in the digits than those of Cynomys. In the 

 foi-e foot the three lobes of the plantar pad are relatively larger, 

 occupying practically the entire width of the foot. The carpal 

 pads also are lai'ger, but the inner does not project laterally in 

 the same way and has no trace of the pollex. Similarly, in the 

 hind foot the plantar lobes are massive and do not exhibit that 

 quadrate arrangement seen in Cynomys and Citellus. Behind 

 the outer lobe of the plantar pad there is a hemispherical external 

 metatarsal, and behind the inner plantar a short internal meta- 

 tarsal with ill-defined posterior border. (Text-fig. 52, C, D.) 



A peculiarity of the feet of this species of Martnota is the 

 complete absence of the pollex. Miller noted this vcl twenty 

 skins, Tullberg's figure showed the same thing, and I have not 

 succeeded in finding a trace of this digit in some half-a-dozen 

 examples I have seen. On the other hand, Miller records the 

 presence of the pollex with a flattened nail in M. hohak, the other 

 European species. The presence of a rudimentary thumb is 

 cited by Blanford in his generic diagnosis of M. himcdayana, 

 hodgsoni, and cauclata, and American writers testify to its 

 retention in M. monax and other N. American species. 



By the structure of the feet the Marmotine genera may be 

 arranged as follows : — 



a. Feet very powerful ; lobes of plantar pads and carpal pads 

 larg-e, metatarsal pads retained. 



h. Pollex suppressed Marmota. 



h '. Pollex retained Ilarmotops * nov. 



a'. Feet at most moderatel}'^ powerful ; lobes of plantar pads 

 and carpal pads smaller, no metatarsal pads. 

 c. Feet comparativelj' stout, inner carpal pad projecting, a 



long claw on pollex Cynomys. 



c'. Feet comparativelj^ slender ; inner carpal pad normal ; 



pollex with nail Citellus. 



g. Feet of the Flying Sqim'rels (Petauristidse). 



Apart from the cartilaginous rod supporting the patagium and 

 jointed to the wrist just behind the outer carpal pad, the fore 

 feet of the Petauristida^ closely resemble those of the typical 

 arboreal sqiiiriels. In Petaurista cdbiventer (niagnificus) f the 

 claws are long and strongly curved. The digits also are long and 

 markedly unequal in length, the fourth being considerably longer 

 than the third and fifth, which are subequal and surpass the 

 second. On the specimen examined there is practically no 

 external trace of pollex and none of the nail. The three lobes 

 of the plantar pad and the carpal pads are large and striate all 

 over. (Text-fig. 55, A.) 



* Tjpe, M. monax. 



t For the specific names here used for Petaurista (olim Fteromys), see Wroughton, 

 Journ. Bombay Nat. Hist. Soc. xx. p. 1012, 1911. 



