Osgood Thirty New Mice of the Genus Peromyscus. 65 



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

 vertebrae, 111; hind foot, 23. Skull of type: Greatest length, 26.3; 

 basilar length of Hensel, 20.3; zygomatic width, 14; interorbital con 

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

 tema, 7; postpalatal length, 9.4; upper molar series, 3.8. 



Remarks. P. fpic&egut 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 spicilegns, show some tendency toward simulus. 



Specimens examined. Total number, 10, from localities in Mexico, as 

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



Peromyscus melanophrys zamorse subsp. nov. 



Type from Zamora, Michoacan, Mexico. Adult male, No. 120,288, U. S. 

 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 

 darker; 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 between fore 

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



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

 braincase fuller and broader; audital "bullae larger; supraorbital beads 

 less trenchant and forming -ridges rather than shelves anteriorly; molar 

 teeth larger; other characters similar. 



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



29. Average of 7 young adult topotypes: Total length, 259; tail verte- 



brie, 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, 66 x 2.7-7 x 2.6. 



Remarks. All the adult specimens of this form thus far examined 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 character of importance. Of 76 specimens of melanophrys 

 and consobrinus, 4 only have pectoral spots, and these are small and in 

 distinct. Of 19 typical specimens of zamorse, all have well-marked pec 

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





