12 ANATOMY OF THE WOOD RAT 



specimen typical of those used for dissection weighed 307 

 grams, after being allowed to drain for five minutes. 



Neotoma (Teonoma) cinerea cinerea. Averages of the 

 collectors' measurements for a series of twelve adults from 

 various portions of the Sierra Nevada in California are as 

 follows. For six males: length of head and body, 222 

 (210-234); tail, 176 (164-185); hind foot, 45.5 (42-49). 

 For six females; length of head and body, 218 (208-229); 

 tail, 165 (158-179); hind foot 43 (41-45). A specimen, 

 unusually large but typical of the three used for dissection, 

 weighed 395 grams after having drained for five minutes. 



From the above averages it is apparent that the females 

 are consistently smaller than the males in length of head and 

 body. This measurement of the females constitutes the 

 following percentages of the same measurement for males: 

 for Homodontomys, 96; Neotoma, 95.5; and Teonoma, 98.2. 

 In consideration of the fact that long tails are especially 

 subject to accidental shortening during life, the slight sexual 

 difference in the length of this member as indicated may or 

 may not be trustworthy. The sexual difference in the length 

 of the hind foot is insignificant except for Teonoma, in which 

 the foot of the female is 94.5 per cent that of the male. 



It will be seen that for head and body length of males, 

 Neotoma is 87.4 per cent of Teonoma, and Homodontomys is 

 85.8 per cent of the same animal. This probably indicates 

 to a fair degree of accuracy the true difference in body 

 measurement of the three species considered. Having no 

 real connection with this is a comparison of the body weights 

 of three of the specimens, representing the three subgenera, 

 which were dissected. The figures are illustrative only of 

 the differences in the cubic capacity, and hence mass, of the 

 three series available, and are not considered to be repre- 

 sentative of the true relational differences as found in animals 

 of like age and development. The weight in grams of the 

 specimen of Neotoma was 59 per cent of that of Teonoma, 



