PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL, 71 



but these give only a hint of the detailed bony structure of the 

 shell. 



The thickness of the bone of the carapace, as in the type, is com- 

 paratively heavy. Viewed from above (see Plates 2 and 3), the 

 carapace is suboval in outline, being wide and broadly rounded 

 behind. It gradually narrows toward the front, the anterior border 

 being truncate with a broad but shallow emargination above the 

 neck. 



s. 2. — Carapace op Terrapbnb canaliculata 

 3ay. No. 25-144, Amhbrst College Mu- 

 seum, v. S. 1, FIRST vertebral SCUTE ; 

 V. S. 5, FIFTH VERTEBRAL SCUTE. ONE-THIRD 



natural size 



Fig. 3. — Carapace op Terrapene canaliculata 

 Hat. No. 25-145, Amherst College Mu- 

 seum. OXE-THIRD natural SIZE 



The carapace of No. 11,428 U.S.N.M. has a greatest length in a 

 straight line through the middle of 262 mm., and a greatest width 

 across the eighth peripherals of 185 mm.; the width thus being 

 0.70 of the length. At the center the shell has a height of about 

 110 mm. The other specimens have the same proportions. The 

 sulci outlining the scutes are narrow but well defined and those 

 bounding the vertebrals are especially deep and conspicuous. 



Along the center of the back within the area of the vertebral 

 scutes, the carapace is somewhat flattened. A low, rounded keel 

 is present, being more especially conspicuous on vertebral three. 



