SCIURIDiE— SCIURUS LEUCOPS. 755 



Lichten stein's MS. name hypoxanthus has of course priority over both, 

 but seems not to have been published except through this incidental refer- 

 ence to it by Geoffroy; and indeed there is no proof that the specimens so 

 named were not referable to the true aureogaster of F. Cuvier. 



Dr. Gray's M. griseqflavus and M. lencops are both described on the 

 same page; and, although griseqflavus stands first, I adopt the name leucops as 

 agreeing better with the specimens figured and described by Geoffroy, while 

 they come also from substantially the same locality; but I at the same time 

 believe griseqflavus to be specifically the same, notwithstanding the more 

 uniform coloration of the dorsal surface. 



A comparison of Geoffrey's description and figures with those given by 

 Cuvier shows at once the wide differences between them, which Geoffroy 

 himself thus notices : — " En comparant cette description a, celle de M. 

 Fre'de'ric Cuvier ou a l'un des individus qui nous sont venus en 1829 et en 

 1831 de la Californie et du Mexique, on reconnaitra imme'diatement de nom- 

 breuses et remarquables analogies avec ceux-ci, mais aussi de notables diffe- 

 rences. L'Ecureuil de la Venus, en meme temps qu'il manque inferieurement 

 de la couleur rousse qui serait caracteristique pour l'espece scion les auteurs, 

 plus de roux sur les parties supdrieures ; et cela, nou-seulement sur la croupe 

 et la nuque ou le roux domine, mais meme surledos, oil les poils ont unezone 

 rousse dont d'autres individus ont a peine un vestige. L'Ecureuil de la Venus 

 ne devrait-il done pas etre considere com me une espece voisine, mais dis- 

 tincte du Sciurus aureogaster ou hypoxanthus?" He refers to the wide range 

 of individual variation presented by several well-known species, and is influ- 

 enced by this in referring the specimens collected by the Venus to Cuvier's 

 S. aureogaster. 



In size and proportions, there is little difference between the present 

 species and S. aureogaster, but the difference in coloration is so pronounced 

 and of such a character as to leave little doubt of their distinctness. In S. 

 aureogaster, the hairs of the dorsal surface have, in some specimens, a pale 

 central narrow ring of rust, but often the hairs are wholly black beneath the 

 surface and merely narrowly tipped with white. None of the sixteen speci- 

 mens of S. aureogaster before me show any approach to any of the six 

 specimens of S. leucops, yet more abundant material may show that they are 

 not specifically separable. Among the specimens from Tehuantepec are 

 typical representatives of both forms. 



