126 Bulletin American Museum of Natural History. [Vol. XXXI, 



Mulege, April 5; 2 males, 1 female, Concepcion Bay, April 7-8; 1 female, 

 San Bernado Mountains, May 15; 1 juv., Miraflores, April. 



40. Peromyscus eremicus eremicus Baird. Desert Mouse. 

 Female, San Francisquito Bay, April 10. 



41. Peromyscus eremicus tiburonensis Mearns. Tiburon Desert 



Mouse. 



Two males, 1 female, Tiburon Island, April 12-13. 



42. Peromyscus guardia sp. nov. Angel Island Mouse. 



Larger than eremicus, in color at least as pale; upper outline of skull less arched; 

 skull similar in general to that of eremicus, but zygoma more compressed anteriorly 

 and rostrum decidedly longer. Incisive foramina rather short, not reaching anterior 

 plane of first molars; interpterygoid fossae broader; audital bulla? larger. 



Type No. 31907 female. 



Measurements: average of two specimens, total length, 208; tail, 114; 

 hind foot, 24. 



Represented by male and female from Angel de la Guardia Island, 

 April 11. 



43. Peromyscus stephani sp. nov. San Esteban Island Mouse. 



Although near to Tiburon Island, the San Esteban form is clearly not very 

 nearly related to P. tiburonensis. In color it is close to typical eremicus; the tail 

 averages shorter and the hind foot larger. 



P. tiburonensis is one of the smallest of the eremicus group, while the San Esteban 

 form is one of the largest, skull decidedly shorter than in eremicus, dentition about 

 the same; nasals more pointed posteriorly and reaching beyond premaxillaries. In 

 eremicus the contrary is true — the premaxillaries exceed the nasals. Posteriorly 

 the frontals meet at an angle on the median line, instead of forming a curve as in 

 eremicus. 



Type, No. 31961, male. 



Measurements, average of four specimens: total length, 195; tail, 97; 

 hind foot, 22. 



Represented by 2 males and 2 females, San Esteban Island, April 14. 



44. Peromyscus eremicus carmeni subsp. nov. Carmen Island 



Desert Mouse. 



Generally similar to P. e. eva, but back rather grayer and general color less 

 rufescent, under parts more creamy white. Specimens vary from white to creamy 

 white beneath; foot larger; teeth larger and tooth-row longer. 



Type No. 31885, male. 



