140 Mr. 0. Thomas 0)i the Grouping of 



of most of tlie species, and to make an attempt to classify 

 them more satisfactorily. 



Recently * Mr. Osgood has proposed the subgeneric name 

 Aidiscomys for a group of species some of which had been 

 referred to Reithrodon and otiier.s to Phyllotis, and which I 

 had ))laced in Euneomys when last writing on the subject f. 

 This subgenus I am prepared to recognize, though I slill 

 consider it more nearly allied to Euneomys than to Phyllotis, 

 to which Mr. Osgood assigns it. 



The position of the whole group among S.-American 

 Muridse may be seen in Wingers synopsis \ of Lagoa Santa 

 Muridse, where they would all fall under what he calls 

 " Hesperomys,^^ though he did not have occasion to deal with 

 the more hypsodont Euneomys series, none of which occur 

 at the locality he was writing about. 



The group divides broadly into two — the slenderly built, 

 slender-footed, and more brachyodont Phyllotis and Eligmo- 

 dontia seiies, and the stoutly built, Microtine-looking, thick- 

 footed, and more hypsodont Euneomys set. 



\\\ working out these animals I have largely used the 

 external characters of build (ears, feet, and mammse), as the 

 characters of the skull and dentition do not suffice to indicate 

 all the natural groups. 



Eligmodontia, F. Cuv., 1837. 



Size small. Form delicate. Tail medium, about as long 

 as or rather longer than the head and body, well-haired, 

 slightly pencilled terminally. Feet characteristic; palms 

 and soles hairy ; in the former the outer part is occupied by 

 two large hairy cushions, the anterior of which bears the 

 two outer digital pads and the posterior the outer carpal pad 

 as quite inconspicuous smooth places on the otherwise hairy 

 surface ; of the two cushions the posterior is by far the 

 largest and most conspicuous. Soles also with hairy cushions, 

 the posterior sole-pad obsolete. Mammte 2 — 2 = 8. 



Skull small, delicate, unridgcd, without special charac- 

 teristics. 



Type. E. typus^ F. Cuv. (syn. Mus elegans, Waterh.). 



* PuLl. Field Mus. x. p. 190 (1915). 



t Ann. & Mag-. Nat. Hist. (7) viii. p. 254 (1901). 



\ Gnavere fra Lagoa Santa, p. 12 (1887j. Winge's synopsis is, a3 

 usual, an admirable presentation of the natural relations of the genera, 

 but to bring its nomenclature up to date Holoc/iilus must be read for 

 Si(/modon, Akodon for Hahrothrix, and Ori/zonu/s for Calomys. 



