56 THE EXTINCT BATRACHIA, EEPTILIA 



Incertae sedis. 



PIRATOSAURUS, Leidy. 



PIRATOSAURUS PLICATUS. Leidy. 



Cretaceous Rept. N. Am., 29, 30, Tab. 



Cretaceous of Red River Settlement, Lat. 49 deg., Northern Minnesota. Described from a tooth. 



THECODONTIA. 

 Owen in part. 



In this suborder we have a singularly generalized group, combining characters of 

 lizards, crocodiles and Sauropterygians. The neural arch of the vertebrae united by suture 

 and the slightly biconcave centrum, resemble the last two, so also the abdominal ribs. 

 The limbs are rather crocodilian, the position of the nares, Plesiosaurian. The clavicle is 

 lacertian, while the three vertebrae of the sacrum and the femur are between these and 

 the Dinosauria. 



The most important characters distinguishing these animals from the Sanropterygia 

 are the presence of an elongate sacrum and the more ambulatory form of limbs. 



Our knowledge of the order is almost confined to Belodon Meyer, and is derived from 

 that author's descriptions of those large and remarkable reptiles derived from the Keuper 

 of Wiirtemburg, the Belodon kapfii Meyer, B. plieningeri Miinst., and B. planirostris 

 Meyer. 



The American species of the order are known only from the valuable collections made 

 by Wheatley at Phcenixville, Pa., and by Emmons at Deep River, in Chatham county, 

 in North Carolina. The former are in my hands for examination and description, and 

 will be the subject of an appendix to this work. 



BELODON, Meyer. 



Although this genus does not present the swimming extremities of Plesiosaurus and 

 Nothosaurus, its structure in this respect is not much more different from them, than 

 that of the marine turtles is from the terrestial families of the same order. The 

 structure of the sphenoidal region, the peculiar position of the external nostrils, almost 

 above the orbits, with the rhizodont dentition, are points in which they agree. The 

 position of the exterior nares cannot be regarded as an ordinal character, since we see 

 what remarkable differences of position it exhibits in the existing family Varanida;. 

 There is is every probability that these animals were aquatic. The posterior position of 

 the nostrils, like that in many other marine animals, enabled them to plunge the long 

 muzzle beneath the surface of the water or mud without interfering with respiration. 



The dentition of the posterior parts of the mouth has been shown by Von Meyer to 

 be quite different from that of the anterior regions; the latter are prehensile, that is 

 elongate conic, the former cutting, i. e., flattened, broader and with trenchant edges. 



