PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 437 



have been able to make up from the literature at command, will be 

 found at the close of this article. 



Establishment of the genus Xerobates. — In 1857, Louis Agas- 

 siz placed the American gophers in the new genus Xerobates, a distinc- 

 tion which has been accepted by Cope,* Gray, and other herpetologists. 

 The characters of the genus are based on the form of the alveolar sur- 

 faces of the jaws and on the form of the fore feet and claws. The latter 

 characters, however, in my opinion, are of less generic value than the 

 former, since X. Berlandieri, which agrees with X. polyphemus and X. 

 Af/assizii in form of alveolar surface, has fore feet but little comjiressed; 

 and even in the two last-named sj^ecies the amount of compression varies 

 considerably. The bluntness of the claws is due largely to the nature 

 of the soil in which the animals live and to their habit of burrowing. 

 The claws of the young, in all the species, are sharp, and but little 

 compressed, although almost perfectly straight. 



History of Xerobates Agassizii. — The history of the scientific 

 discovery of the western gopher, unlike that of its eastern relative, is 

 a very simple one. The tortoise was first made known to science by 

 Dr. J. G. Cooper in a paper on -'Xew Californian Animals," read before 

 the California Academy of Scienci-s, July 7, 18G1, aud published in the 

 second volume of the proceedings of that society, issued in 1863. The 

 description is as follows: 



" Professor Baird thinks with me that the following will undoubtedly 

 prove a new species, after a comi)arison of specimens : 



"Xerobates agassizii, — Agassiz's Land-Tortoise. 



^^ Spec. char. — Young, with the carapax higher and more arching than 

 in X. carolimis; the margin serrate all round, the primary disks of the 

 scales projecti}ig from a tenth to an eighth of an inch. Color of pri- 

 mary disks entirely pale yellow, the annual rings of growth only being 

 dark brown. (Young just hatched, probably all yellow.) 



'■'- Eemarlis. — Closely resembles X. caroUnus, the 'Gopher' of Florida 

 and the other Cotton States, of which no descrij)tions accessible are 

 full enough to enable me to point out all the differences. But as an- 

 other species intervenes between the range of that and this one, namely, 

 X. berlandieri of Agassiz, found in Southern Texas and Mexico, I feel 

 confident that comparison of specimens will show constant distinctions 

 between them. From X. berlandieri it differs even more than from 

 caroUnus. Besides the serrate margin, which is most distinct in my 

 youngest specimens (four years), while Agassiz's figure of the young 

 has no serrations, and different coloration, it has but twenty-four in- 

 stead of twenty-six marginal scales (abnormal in his figured specimen?), 

 and the primary disk of the vertebral scales is more than half as long 

 (antero-posteriorly) as it is broad, instead of about twice as broad as 

 long. The other scales also differ in details of form. 



* Cope, BuU. U. S. G. & G. Survey, iv, 1878, p. 393. 



