COUES ON GEOMYS AND THOMOMYS T. CLUSIDS. 265 
of talpoides and its conspecies I know of. The color is equally diagnostic. 
We miss the peculiar blackish area in which the ears of all other Thomomys 
are set, and we find instead a blackish snout. The pallid yellowish-gray of 
the upper parts is as different from any of the interminable variations of color 
of other Thomomys as that of Geomys castanops in comparison with G. bursa- 
rius. The whiteness of the fur_to the very roots, on the under parts, is a 
striking character. 
The specimen was procured in a region where the true talpoides is also 
found in abundance. 
It seems to be the fortune of monographers who have found it necessary 
to reduce various species previously established to geographical races or mere 
synonyms, that they should have at the same time new ones of their own to 
propose. But I see no help for this. New species are not, to me, the alto 
gether desirable things they seem to some ; and my growing dislike to find 
them out keeps pace with my increasing knowledge of our ignorance respect 
ing old species ; nevertheless, there is no escape from them at present, at fre 
quent intervals, and of course the sooner they are all indexed binomially the 
better. Having no material for the further elucidation of the characters of 
Thomomys clusius, I may close with the remark that, if the unique specimen 
is not a pure "sport," it is a perfectly good species. 
The name chosen for this species commemorates a peculiar trait of the 
whole family Geomyidce their remarkable and not generally known habit of 
plugging up the numerous openings of their extensive subterranean tunnels. 
This name, in connection with several others, completes a sort of epitome of 
the history of the family. They are underground animals (Geomys) that 
throw up heaps of earth (,9-oyuo?, a pile Thomomys} and close the entrances 
of their excavations (clusius) ; they are mole-like in many respects (talpoides) ; 
they are peculiarly provided with pouches (bursarius) ; and they feed on roots 
(bullrivorus] 
34 COL, 
