154 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Thomomys jacinteus, new species. 

 San Jacinto Gopher 



Type.— MRle, adult; No. 21235, Mus. Vert. Zool. ; Round 

 Valley, 9000 feet altitude, San Jacinto Mountains, Riverside 

 County, California; September 15, 1914; collected by H. S. 

 Swarth; orig. No. 10012. 



Diagnosis. — A Thomomys of the alpinns group of species. 

 Size medium; coloration dark; skull long and narrow, but 

 faintly ridged, and with relatively straight top in lateral 

 profile. 



Material. — Nineteen skins-with-skulls from San Jacinto 

 Peak: Nine (Nos. 21229-21235, 1761, 1762) from Round 

 Valley, 9000 feet altitude; ten (Nos. 2188-2197) from Tah- 

 quitz Valley, 8000 feet altitude. Of these, nine are obviously 

 young; seven are males, twelve are females. 



Comparisons. — As compared with topotypes of Thomomys 

 altivallis Rhoads, its nearest relative geographically, the new 

 species is decidedly smaller in general size (see accompanying 

 tables of measurements), the tone of coloration is slightly 

 browner, there is more or less white about the face, the whole 

 skull is much narrower (except for interorbital constriction), 

 there is less of angulation and ridging, the nasals are shorter, 

 and the dorsal outline is more nearly straight in lateral profile. 

 From Thomomys neglectus Bailey, from the San Gabriel 

 Mountains, as originally described (Proc. Biol. Soc. Wash., 

 Vol. 27, 1914, p. 117), jacinteus evidently differs notably in 

 much less blackish coloration, in presence of more or less 

 white about the face, and in less elongated and straight-topped 

 skull. From topotypes of Thomomys alpinus Merriam, from 

 the Mount Whitney region, jacinteus differs in decidedly 

 browner and darker, less grayish, coloration, in much less 

 squarely spreading zygomatic arches, in narrower braincase, 

 and in shorter and posteriorly less attenuated nasals. From 

 the species of gopher on the immediately adjacent lower 

 slopes of San Jacinto Peak (T. nigricans Rhoads, of Upper 

 Sonoran and low Transition), jacinteus differs in decidedly 

 larger general size and notably larger ears and front feet, in 



