142 



ANATOMY OF THE WOOD RAT 



needed in a consideration of functional morphology of mam- 

 mals of high specialization is merely a standard of com- 

 parison between the fore and hind limbs as a whole and their 

 several segments, as well as of various other parts of the body. 

 For practical purposes, then, the functional length of the 

 fore limb should be considered as the distance from the 

 scapular-humeral joint to the ground when the animal is in 



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 cofl^co>o 



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Fig. 30. Osteological details of the right scapula of Teonoma. A, 

 Lateral aspect. B, Medial aspect. 



standing posture with the limb extended in a straight line. 

 In a plantigrade mammal this will be to the sole of the heel; 

 in a digitigrade one, to the tip of the toes, the hoof, or what- 

 ever portion of the foot rests upon the ground. In the genus 

 Neotoma the manus is relatively small and weak, and the 

 animal may be considered as really plantigrade in this 

 member (Plate 1 shows the fore foot as more digitigrade 



