96 



ANATOMY OF THE WOOD RAT 



caecum, which is greatly developed in the present genus. 

 In two specimens its length beyond the small intestine was 

 103 and 110 mm. The enlarged base was prolonged into 

 the neck, of only shghtly reduced diameter, between the 

 caecum proper and the cohc loops, which latter make two 

 and one-quarter turns. In one specimen there was an 

 additional reverse turn. 



In three specimens of Neotoma the caecum was 85, 108, 

 and 110 mm. in length, and as much as 27 mm. in diameter. 

 The neck, posterior to the small intestine, was extremely well 

 developed, of as large diameter as the caecum proper, and 



Fig. 20. Caecal portion of the large intestine of Homodontomys. 



became only slightly smaller throughout its length of^25 

 mm. to the colic loops, which resembled those of Teonoma. 

 In Teonoma the caecum measured 120 and 118 mm. in 

 two specimens. The neck was constricted and well dif- 

 ferentiated from the caecum proper, being but 10 mm. in 

 width, and 22 and 30 mm. in length, with thicker walls. 

 In this subgenus the colic loops were more capacious, but 

 there was only one true loop, the ''second" being a U- 

 shaped tract, followed by a half loop showing some indi- 

 vidual variation. 



