202 Annals of the Carnegie Museum. 



34 mm.; while the costal scutes have been only about half as wide. 

 The areas occupied by the median scutes are conspicuously sculptured. 

 The sculpture, as shown by the third scutal area, consists of ten or 

 twelve prominent, sharj), uneven, ridges, which radiate forward and 

 outward from the middle of the hinder border of the area. Evidently, 

 a somewhat similar, but less bold sculpture has characterized the areas 

 of the costal scutes ; but these surfaces have been injured so that it 

 cannot be described. There is no evidence of the presence of supra- 

 marginal scutes. 



On the left side the costal and marginal plates have been broken 

 away. The anterior and posterior buttresses of the plastron have thus 

 been revealed ; and it is evident that the anterior one, joining the 

 second costal plate, projected inward a considerable distance, as in 

 Baena, to form the anterior boundary of a lateral chamber, whose 

 po.sterior boundary was formed by the hinder buttress joining probably 

 the sixth costal plate. 



When the costal plates broke away the extremities of the third, 

 fourth and fifth ribs were left adhering in the matrix. These have 

 evidently passed downward deeply against the inner sides of the cor- 

 responding marginal plates, as in Clielydra. Such was probably not 

 the condition in Bacna. The ends of the ribs are terete, not flat as 

 in most other cases. So far as can be determined, there were no fon- 

 tanelles between the costal plates and the marginals. 



Of the plastron all is present except the epiplastrals, and possibly 

 the anterior part of the entoplastron. The plastron resembles closely 

 that of Baena ; but the hinder lobe is not excavated posteriorly, but 

 rounded. There is a considerable fontanelle between the inner ends 

 of the mesoplastra. The presence of this may be due to the immaturity 

 of the specimen ; but judging from the closeness of all the sutures of 

 our specimen, and from the fact that in Baena the bones soon coossify, 

 it seems probable that the fontanelle would persist till a late period of 

 life. 



The anterior, as well as the posterior, lobe has a width at the base 

 of 36 mm. The posterior has a length of 30 mm., and the anterior 

 has probably been about as long. The posterior lobe diminishes in 

 width rather rapidly backward. The entoplastron has been unusually 

 long and narrow in its hinder portion. Nothing can be determined 

 regarding the presence of intergular and gular scutes. The mesoplas- 

 tron is narrowed at the inner end, as in some species of Baeua. Each 

 is traversed by the pectoro-abdominal sulcus. 



