2 PEOCEEDINGS OF THE ISTATIOSTAL MUSEUM vol.73 



tion or tuberosity of greater or less prominence ; and these are placed 

 along the sharp border of the carapace, one at the rear of eacli 

 marginal scute. 



From the carapace and plastron of the matamata here studied the 

 scutes have been removed, and this has brought into view the super- 

 ficial (epithecal) bones mentioned above. The epithecal bones of the 

 plastron (not figured) occupy about the same positions as shown on 

 plate 2 of the paper in the Journal of Morphology; but are more 

 strongly developed. The one on the right gular scute spreads back- 

 ward on the humeral scute. No such bone occurs on the hinder outer 

 corner of the humeral scute areas of either the new specimen or of 

 the ones previously described. From the front of each pectoral scute 

 to the rear of the plastron there is a nearly continuous series of thin 

 overlying bones. In the United States National Museum is a 

 mounted skeleton of Chelys (Cat. No. 29545) whose epiplastron has 

 along its whole lower border a rough surface which once supported an 

 epithecal bone, where widest about 10 mm. 



On the carapace (pi. 1) a minute ossicle is seen on the rear of the 

 nuchal scute. On the boss situated about three-fourths of an inch 

 in front of the hinder border of the first vertebral scute a scale of 

 bone is to be expected. It is not present exactly there, but just a 

 little in front of this there appears once to have been a narrow scale 

 about 11 mm. long. Close to the rear of the second vertebral scute 

 is a very distinct irregular ossicle, 10 mm. long and nearly as wide. 

 Surmounting the tuberosity of the third scute is a bone about 12 mm. 

 square forming an inset in the fifth neural bone. A smaller ossicle 

 caps the fourth tuberosity. On the crest of the sharp ridge travers- 

 ing the fifth vertebral scute area are several pits from which ossicles 

 seem to have been torn away with the horny scute. 



On the lateral keel of the left side the first, second, and third tu- 

 berosities support each a distinct bone, but there is none on the fourth. 

 The same statement may be made about the tuberosities of the right 

 lateral keel, but an ossicle on the third was evidently carried away 

 on the horny scute. 



On the left border of the carapace no epithecal bone appears on 

 any of the first three tuberosities, but on the second scute, at the 

 middle of the border, is a scale 10 by 15 mm. which may be looked 

 upon as having migrated from the tuberosity just behind it. On 

 the fourth tuberosity is a pit showing that a bone was torn away with 

 the scute. On the left fifth scute area is a nearly circular bone 10 

 mm. in diameter, capping the boss. No superficial bone is seen on 

 the sixth marginal scute. On the rear of the seventh scute area is a 

 deep pit where a bone 20 mm. long was lodged ; in fact, a part of it 

 remains. On the rear of the eighth scute area is a scar or rough sur- 

 face from which a superficial bone has been removed. Immediately 



