642 THE MONTHLY BULLETIN. 



shoulder patches, deep cinuamou-brown, the hairs individually being black, tipped with 

 cinnamon ; middle of back darker in tone than top of head ; spot above upper eyelid 

 blackish ; cheeks and sides of neck much darker in tone than in beecheiji; vphitish 

 shoulder patches, restricted in exten% dull and indistinct as compared with fisheri and 

 douglasii, even more so than in heeclieyl. Under surface of body very dark in tone, 

 the hairs extensively grayish bister at bases and tipped with cinnamon buff. Tail 

 and feet colored as in heecheyi. 



Color variations. — The type and one other specimen show a black patch on the 

 crown, due to lack of cinnamon hair-tippings ; this, of course, is merely an individual 

 feature. 



The May-taken series at hand shows various transition stages from winter to sum- 

 mer pelage. In most of the specimens the fore parts are in fresh harsh summer coat, 

 while the rump is still covered with the winter coat, showing underfur, and being 

 more or less worn and faded. The tail in some examples is markedly worn and faded, 

 with the usually resulting changes in color. In some specimens the hairs of the 

 tail show but two dark bands instead of three ; but this variation occurs also in 

 other near-related races of ground squirrels. The two skins taken in February are in 

 full winter pelage, showing more or less underfur over the whole body and no signs 

 of molt. The fore parts, as compared with the summer pelage, are less bright in 

 color tones, and the shoulder patches are even less distinctly whitish. Hinder upper 

 surface and tail exactly as in heecheyi of same season. 



Measurements. — Average and extreme measurements, in millimeters, of nineteen 

 full-grown specimens from near Avalon, Catalina Island, are as follows : Seven 

 males: total length, 471 (447-495); tail vertebraj, 189 (175-200); hind foot, 

 59 (55-63) ; greatest length of skull, 60.2 (56.1-63.7) ; zygomatic breadth, 36.9 

 (33.8-39.2) ; interorbital width, 14.8 (13.3-15.9). Twelve females: total length, 444 

 (406-475) ; tail vertebrae, 179 (161-194) ; hind foot, 56 (53-62) ; greatest length of 

 skull, 57.7 (54.0-62.4) ; zygomatic breadth, 35.9 (33.3-37.6) ; interorbital width, 

 14.3 (13.0-15.4). 



Close examination of the series of skulls shows to us no character by which to 

 tell them from heecheyi or fisheri except for average greater size. There is the 

 usual range of variation in proportions, due to age, this factor being judged from 

 degree of wear on the crowns of the molariform teeth. Old skulls are largest, 

 broadest relatively to length, and with most prominent ridges and processes. It is 

 difficult for us to understand how Elliot (1904, p. 263) could have assigned the 

 numerous cranial characters he did to the form he named, except on the ground that 

 he examined but a very few specimens of heecheyi and fisheri and that these 

 happened to be extreme. 



Type locality. — Santa Catalina Island, California (Elliot, 1904, p. 263) ; more 

 exactly, vicinity of Avalon, according to the collector of the type, Mr. John Rowley, 

 in interview. 



Distribution area. — Santa Catalina Island, California. Life-zone, Upper Sonoran. 



Specimens examined. — A total of 21 skins and skulls, all from the vicinity of 

 Avalon, Catalina Island. Two of these (including the type) were loaned us from the 

 Field Museum of Natural History, Chicago ; and nineteen were loaned us from 

 the Museum of History, Science and Art, Los Angeles. 



Only three species of rodents are known to be native to Catalina 

 Island, a harvest mouse, a white-footed mouse, and the Catalina Island 

 Ground Squirrel. This last-named animal is, as in each of the other 

 cases, but slightly differentiated from its counterpart on the adjacent 

 mainland. With little doubt it differs no more from its near relative, 

 the Beechey Ground Squirrel, in general habits and traits, than it 

 does in structure. 



Until the present year very little has been known of the Catalina 

 Island Ground Squirrel. In fact, the original characterization of the 

 race was so unsatisfactory as to leave doubts in the minds of some 

 students as to whether the island animals really differ at all from the 



50 



