60 0'<gnod — Thirty New Mice of the Genns Peromyscus. 



Skull. — About as in P. aUwateri ; somewhat similar to that of P. levijicK* 

 but smaller, witli smaller teeth; lachrymal region less swollen; nasals 

 rather lone and broad; zygosnata somewhat compressed anteriorly, not 

 elbowe<l squarely ; premaxillye usually ending beyond nasals; interpari- 

 etal rather large; audital bullfe quite small, smaller than \nlni}>esov 

 eremicus. 



Measurements. — Type: Total length, 210 ; tail vertebrje, 114 ; hind foot, 

 22. Average of 10 adults from various localities: 200; 112; 21.5. Skull 

 of type: Greatest length, 27; basilar length of Hensel, 19.7; zygomatic 

 widtli,]3.7; interorbital constriction, 4.2 ; nasals, 9.9; bony palate, 3.7 ; 

 {lalatine slits, 4.9 x 2; diastema, 6.:); postpalatal length, 9.4: upper 

 molar series, 3.8. 



Peromyscus attwateri eremicoides subsp. no v. 



'J'l/pe from Mapimi, Durango, Mexico. Adult male, No. 57,71:9, U. 8. 

 National Museum, Biological Survey Collection, December 15, 1893, E. A, 

 Goldman. 



Cliaracler.'i. — Similar to P. atdeaterl, but smaller and paler: skull small 

 and light; audital bulhe very small ; ears small; soles of liind feet naked. 



Color. — Upper parts mixed pinkish buff and dusky, producing the gen- 

 eral effect of pale broccoli brown; lateral line pinkish buff; underparts 

 pure creamy white without trace of pectoral sjfot; facial region between 

 eye and ear grayish; feet and ankles white; tail dusky above, white 

 below. In some specimens, doubtless the younger ones, the general 

 effect is gray, while in otliers a delicate shade of iiinkish buff predomi- 

 nates. 



.S7>-«W.— Similar in general to that of uUiraleri but decidedly smaller ; 

 audital bullfe very small ; nasals short ; interorbital constriction rela- 

 tively wide; rostrum depressed. 



Mensurements. — Type and one topotype: Total lengths, 180; 195; tail 

 vertebra?, 102; 111; hind feet, 20; 21. Skull of type: Greatest length, 

 24; basilar length of Hensel, 18; zygomatic width, 12; interorbital con- 

 striction, 3.9; interparietal, 8.3 X 3; nasals, 8.5; bony palate, 3.5 ; pala- 

 tine slits, 4.5 X 1.5; diastema, 5.8; postpalatal length, 8.5; upper molar 

 series, 3.5. 



Remarks. — This form is readily distinguishable from both attiralerl and 

 pectoralis by its pale color, small ears, and very small skull. Its resem- 

 blance to P. eremicus, }iarticularly in immature and w^orn pelages, is re- 

 markable. The only external characters by which it may be distin- 

 guished are its longer, slightly more hairy tail and pure white ankles. 

 Neither of these characters, however, is to be depended upon, as the tail 

 in eremicus is often quite hairy, and the dusky on the ankle frequently so 

 little developed as to be scarcely apparent. The molar enamel pattern, 

 except in extremely worn teeth, is always diagnostic, eremicoides having 

 the small accessory cusps and eremicus being without them. 



S))ecimevs e.\ amined. —Tota.\ number 10, from localities in Mexico as 

 follows: Coahuila, Jimulco, 4; Durango, Inde, 4, Mapimi, 2. 



