204 



ANATOMY OF THE WOOD RAT 



logical items of Neotoma exhibiting either greater or less 

 development than in the other two subgenera are a result, 

 either direct or indirect, in varying degree, of the habits and 

 habitat predilections of that animal. On the other hand 

 such a detail as the development of the os penis can have 

 nothing to do with what is herein meant by life habits. 

 The separate items regarding bone measurements ex- 



TABLE 3 



Table of Osteological Comparisons Expressed in Percentages 



TBONOMA. 



Cervical vertebrae of trunk length. 

 Thoracic vertebrae of trunk length 

 Lumbar vertebrae of trunk length. 

 Sacral vertebrae of trunk length. . . 

 Caudal vertebrae of trunk length. . 



Sternum of trunk length 



Clavicle of trunk length 



Scapula of functional arm length. . 

 Arm (functional) of trunk length. . 



Humerus of arm length 



Ulna of arm length 



Radius of ulna length 



Fore foot of arm length 



Innominate of leg length 



Leg (functional) of trunk length. . . 



Arm (functional) of leg length 



Femur of leg length 



Tibia of leg length 



Fibula (to notch) of tibia length. . . 

 Hind foot of leg length 



per cent 



13.4 

 37.3 

 31.4 

 17.9 

 119.0 

 31.6 

 13.0 

 45.2 

 47.1 

 52.4 

 57.9 

 82.5 

 30.4 

 45.6 

 73.2 

 65.0 

 43.2 

 43.1 

 58.9 

 40.5 



pressed as percentages and presented in the table above 

 have been already discussed, but a summary is advisa- 

 ble. Comparison of the soft parts may show a more de- 

 tailed record of adaptational speciahzation, did we know 

 enough to interpret them correctly in all cases. But such 

 information is often difficult to obtain, and in an investiga- 

 tion of specialization it is really to the skeleton that we 



