Osgood — Thirlii Xeir Mice of the (fenas Peromyscus. 65 



Measurements. — Average of 3 adult topotypes: Total length, 208; tail 

 verteV)ne, 111; hind foot, 2.S. Skull of type: Ciieatest length, 2(i.3 ; 

 bassiiar length of Heiisel. 20.3; zygoinatie width, 14; interorbital con- 

 stiiction, 4.1 ; nasals, 9.4; bony palate, 3.6; palatine slits, 5.6 x 2; dias- 

 tema, 7; postpalatal lengtli, i).4; upi)er nK)lar series, 3.8. 



Remarks. — P. spirilefjiis is essentially a mountain animal, and is not 

 usually found except at considerable elevations. Apparently the form 

 from the lowlands of Tepic is its only coast representative. This is well 

 characterized by cranial characters, although it does not differ markedly 

 in color, being possibly a shade darker, but in this respect easily within 

 the variation of the typical form. Specimens from Plomosas, Sinaloa, 

 though referable to spicilegus, show some tendency toward sitnulas. 



Spee.lmen.'i examined. — Total number, 10, from localities in Mexico, as 

 follows: Tepic, Navarrete, 2, Rosario, 2, San Bias, 6. 



Peromyscus melaiiophrys zamoree subsp. nov. 



Ti/pe from Zamora, Michoacaii, Mexico. Adult male. No. 120,288, U. R. 

 National Museum, Biological Survey Collection, January 20, 1903, E. W. 

 Nelson and E. A. Goldman. 



Characters. — Similar to P. melanophrys, but averaging slightly larger and 

 ilarker ; a large tawny pectoral spot present ; * skull comparatively broad 

 and heavy, teeth large. 



Color. — Similar in general to that of P. melanophrys, but apparently 

 somewhat darker, the difference in this respect being very slight if any. 

 Adults with a broad band of tawny across pectoral region l)etween fore- 

 legs. Upper side of tail more nearly black than in mehinoplirys. 



Skull. — Similar to that of melanophrys, but slightly larger and heavier ; 

 braincase fuller and broader; audital bulhe larger; supraorbital beads 

 less trenchant and forming ridges rather than shelves anteriorly; molar 

 teeth larger; other characters similar. 



Measurements. — Type: Total length, 260; tail vertebrte, 141 ; hind foot, 

 29. Average of 7 young adult to{)otypes: Total length. 259; tail verte- 

 l)r;e, 144; hind foot, 28.4. Skull.— Two adults : Greatest length, 31.3-32 ; 

 basilar length of Hensel, 25-25.9; zygomatic width, 16.5-16.9; nasals, 

 12-12; upper molar series, 4.7-4.8; -palatine slits, 6.6 x 2.7-7 x 2.(). 



Remarks. — All the adult specimens of this form thus far e.vamined have 

 the tawny pectoral marking highly developed. The majority of the 

 series from Zamora are adolescents and exceptionally dark. Even those 



* The constancy of this character may be doubted, as it is of such irreg- 

 ular occurrence in this genus. In the present case, while not diagnostic, 

 it seems to be a cliaracter of importance. Of 76 specimens of melanophrys 

 and consohrinus, 4 only have pectoral spots, and these are small and in- 

 distinct. Of 19 typical specimens of za)norx, all have well-marked pec- 

 toral spots except 2 plumbeous young, which have only traces. 



