1915.] 



THOMOMYS ALPINUS GROUP. 



67 



wide and spatulate; interparietal rather small, quadrate, narrowing 

 with, age; pterygoids long and low and nearly parallel; interpterygoid 

 fossa not narrowly V-shaped. Dentition relatively heavy; incisors 

 curved abruptly downward and not extending^ much beyond tip of 

 nasals and premaxillse. 



Measurements. — Type ( 6" ad.): Total length, 240; tail vertebrae, 

 82; hmd foot, 32. Topotype ad.): 234, 80, 31.5. Topotype 

 ( 9 ad.) : 232, 76, 29. SJcuU (of type) : Basal length, 40; nasals, 14.5; 

 zygomatic breadth, 24.7; mastoid breadth, 20; mterorbital breadth, 

 6; alveolar length of upper molar series, 8.8. 



Remarks. — At first I was reluctant to separate this high-mountain 

 form from nigricans by skull characters alone, as the skins are indis- 

 tinguishable, but the series of specimens recently collected in Kound 

 Valley in the San Jacinto Mountains (at 9,000 feet altitude) by H. S. 

 Swarth show that the skull characters are well marked and constant. 

 The series of 8 males and 5 females from the type locahty, now before 

 me, have the long, low, narrow, straight skulls of cahezonse ^"ith the 

 same peculiar pterygoids. They differ from cahezonse in larger size, 

 heavier dentition, and much darker color, but show a decided rela- 

 tionship mth that species. The resemblance to nigricans may be 

 entirely superficial just as it is with, fulvus, the three forms being very 

 similar in coloration while evidently quite distinct. A close rela- 

 tionship with neglectus is indicated by the general type of skull, but 

 that form is much more extreme in its characters. From martirensis 

 the present form differs in a rather straight instead of well-arched 

 outline of skull. The two other high-mountain species with which 

 comparison is sug:gested are altivallis and alpinus from similar alti- 

 tudes in the San Bernardino Mountains and the Sierra Nevada. Of 

 these, altivallis is at once eliminated on account of its larger size and 

 its broad, well-arched, and massive skull, protruding incisors, and 

 narrowly contracted pterygoids. Thomomys alpinus, while so similar 

 in general size and appearance as strongly to suggest relationship, 

 has a very different type of skull; shorter, wider, and more arched 

 zygomata (widest posteriorly) ; and too many detailed differences to 

 admit of close relationship with the present form. 



Specimens examined. — Total number, 25, as follows: 

 California (higher levels of San Jacinto Mountains) : Round Valley (9,000 feet alti- 

 tude) 8; San Jacinto Peak (10,200 feet), 1; Tahquitz Valley (8,000 feet), 13; 

 Tamarack Valley (9,400 feet), 2; uncertain locality along the trail (8,500 feet), 1. 



THOMOMYS MARTIRENSIS Allen. 

 San Pedro Martir Pocket Gopher. 

 Thomomys fulvus unartirensis Allen, Bui. Am. Mus. Nat. Hist., X, 147. 1898. 



Type. — Collected on San Pedro Martir Mountains (at 8,200 feet 

 altitude). Lower California, by A. W. Anthony and E. C. Thurber, in 

 May, 1893. Type specimen in Am. Mus. Nat. Hist, 



