338 University of California Publications in Zoology [Vol. 10 



of cranium, shape of interparietal, width of interorbital constric- 

 tion, development of supra-orbital "bead." shape of nasals, rela- 

 tive size of audital bullae, and outline of palate posteriorly. 



First, as leading to clearness in the discussion to follow, we 

 herewith present a comparative diagnosis of intermedia and 

 desertorum, the former based upon a series from the vicinity of 

 San Diego, the latter upon a series from along the Colorado 

 River between Needles and Yuma. 



Double-column Diagnosis of Neotoma i. intermedia versus N. i. 



DESERTORUM 



Neotoma i. int( rmedia 

 General coloration above dark: 

 blackish mid-dorsally, mixed with 

 clay color, this most pure along 

 the sides and about the face; be- 

 neath white, with much deep 

 plumbeous at bases of hairs 

 throughout (occasional examples 

 with hairs on small pectoral patch 

 white to base); ankles dusky: tail 

 black above. 



Pelage harsh: hairs relatively 



still' and coarse. 



Size large: average 13 males, 

 length 336, tail vertebrae 159, 

 hind foot 34.3, ear 30.4. (For fe- 

 males and range of variation see 

 figs. a-c). 



Tail "long": ratio of tail to 

 body in 13 males, 89%. 



Skull large throughout, this in- 

 volving all features, save that 

 rostrum and nasals are relatively 

 longer and narrower, while audi- 

 tal bullae are actually as well as 

 relativelv less inflated. 



N( ni mini i. ili xi rtorum 



General coloration above pale: 

 sepia mid-dorsally, mixed with 

 pinkish buff, this color clearest 

 anteriorly and along sides; be- 

 neath white, with slight amount 

 of pale plumbeous at bases of 

 hairs except on pectoral region 

 and narrow line mid-ventrally 

 which are pure white; ankles 

 white; tail grayish brown above 

 (variable to blackish). 



Pelage soft: hairs relatively 

 fine and silky. 



Size small: average 10 males, 

 length 288, tail vertebrae 134, 

 hind foot 30.8, ear 28.5. (For fe- 

 males and range in variation see 

 figs. a-c). 



Tail "short": ratio of tail to 

 body in 10 males, 87%. 



Skull small throughout, this in- 

 volving all features, save that 

 rostrum and nasals are relatively 

 shorter and hence blunter, while 

 the audital bullae are distinctly 

 larger, more inflated. 



Length of ear is not included in above tabulation, because 

 found by us to be of inappreciable difference in size propor- 

 tionally. It will be noted that the emphasized character of rela- 

 tive tail length is really verv small! 



