MUllIDAE— 8IGMODONTES— IlESPUUOMYS LKUCOPUH. fiO 



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We now desire to invite attention to the supposed species named Hes- 

 peromys "gambeli", in proposing which Professor Baird remarks pertinently: — 

 "This species, ia size and general appearance, represents very closely the 

 Hesperomi/s leucopus of the Eastern States, to such degree, in fact, that I have 

 not found any easily-expressed characters to separate them." We ourselves 

 fail to appreciate any differences whatever that are applicable to even a fair 

 proportion of the specimens examined, though some are paler than ordinary 

 hucopus I we cannot even make Professor Baird's qualified expressions hold 

 good. This, however, being merely our opinion, good for what it may be 

 worth, we are called upon to prove the point. With all the original speci- 

 mens and many additional ones before us, we first present a table, and will 

 then discuss the same. 



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