3/2 ON MAMMALIA FROM CKNTRAL MEXICO. [Apr. 18, 



7. SCIURUS ABERTI, Woodll. 



Two specimens. Ciudad, Aug. 7 and Oct. 14, 1881. 



This is the first occurrence recorded of the present species in the 

 region included in the ' Biologia Central!- Americana.' It has been 

 hitherto only known from Colorado, Arizona, and New Mexico. 

 These specimens, however, exactly agree with the figure given by 

 Dr. Baird of his S. cnstanonof.us ', which Mr. Allen has determined 

 to be a synonym of S. aberti ". 



8. SciURXJS GRiSEOFLAVus, Gray. 



Two specimens. Ciudad, Sept. 19 and Nov. 14, 1881. 



9. Tamias asiaticus, var. quadrivxttatus, Rich. 



Two specimens. Ciudad, July 6, 1881. 



This is the first time that specimens of the genus Tamias have 

 been obtained in Mexico. It is true that Mr. Allen ^ has stated his 

 opinion that another species, T. harrisi. And. and Bach., probably 

 extends into Western Mexico ; but the evidence was not sufficient 

 for Mr. Alston to include the genus in the ' Biologia.' It is interest- 

 ing to observe that it is the bright-coloured variety quadrivittatus, 

 and not the pale washed-out var. dorsalis of New Mexico, Nevada, 

 and Arizona, that is now found by Mr. Forrer in Durango. This 

 fact is of course confirmatory of Mr. Allen's opinion that T. dorsalis 

 is not specifically separable from T. asiaticus, since we find the usual 

 northern form reappearing as soon as the desert region inhabited by 

 T. dorsalis is past and the country is again fertile and well wooded. 



10. Spermophilus grammtirus, Say. 

 One specimen. Ciudad, August 20, 1881. 



11. Hesperomys leucopus, var. sonoriensis, LeC. 

 Two specimens. Ciudad. 



12. OCHETODON MEXICANtTS, De SuUSS. 



Two specimens. Ciudad. 



13. Arvicola mexicanus, De Sauss. 

 Two specimens. Ciudad. 



14. Thomomys talpoides, Rich, 



Two specimens. Ciudad, July 24, 1 88 1 . The most southern loca- 

 lity yet recorded. 



15. Tatusia novemcincta, Linn. 



One specimen. Ventanas, Sept. 14, 1881. 



16. DiDELPHYS MURiNA, Linn. 



Two specimens. Ventanas. The most northern locality recorded. 



1 Mamm. N. Am. p. 266, pi. Ixv. ' Mon. N.-Am. Eod. p. 735, 1877. 



" Tom. cit. p. 812. 



