AND AVES OF NORTH AMERICA. 



122-A 



TRIASSIC DINOSAURIA. 



CLEPSYSATJRTTS, Lea. 

 CLEPSYSAURUS PENNSYLVANICUS, Lea. 



Journ. Ac. Nat. Science, Phila., II., 185, Tab. Emmons' N. Amcr. Geol. p. 07 (in part). 



This species is a Dinosaurian, as demonstrated by an ischium which I found among the original specimens, and 

 which resembles in some degree that of Lselaps and Megadactylus. The genus appears to be closely allied to PalffiO- 

 saurus. It was probably a "bird-track" maker. The remains from North Carolina referred to it by Emmons, belong 

 in large part to a Belodont reptile. 



Triassio Sandstones, Lehigh County, Pa.; Phcenixville, Pa. ; Triasslo Coal Measures, Chatham Co., N. Carolina. 



MEGADACTYLUS, Hitchcock. 



Supplement to the Tchnology of New England, p. 39, 1805. 



This genus is indicated by remains in a more or loss fragmentary condition, from the 

 red sandstone rocks of the Valley of the Connecticut, from the neighborhood of Spring- 

 field, Massachusetts. They were found by William Smith, while engaged in superintend* 

 ing some excavations made at the armory, which required blasting. 



The remains consist of four caudal, and one dorsal vertebra?, the greater part of the 

 left fore foot with distal portions of ulnar and radius; the greater part of the left femur, 

 proximal end of left tibia, greater part of left fibula, tarsus and hind foot, including a tar- 

 sal bone, perfect metatarsus, proximal end of a second metatarsus, parts of the distal end 

 of a third, and parts and impressions of lour phalanges. Also, the greater part of both isehia. 



These fragments demonstrate the former existence in the region in question, of a form 

 of the Dinosauria, not far removed in some points from the Palseosaurus of the English 

 Trias. Its pertinence to the Symphypoda is suggested by the apparent absence of the 

 calcaneum; but tins is uncertain, for that element may have been lost. In Compsognathus 

 the additional peculiarity of the persistence of but two carpal bones is presented, which 

 according to Gegenbaur, should correspond with those of the first row of ordinary Reptilia, 

 while those of the second have disappeared. In Megadactylus those of the first series are 

 present, viz; the radiale and probably ulnare, and one of the second row, very much re- 

 duced, opposite to the second metacarpus. There is space for a second one of the second 

 series, but it does not appear in the matrix, while the ulnare is probably lost. 



The bird-like tendencies of this type have been indicated above, and the very ornithic 

 character of the bones of the present form is also very marked. The walls of the long 

 bones are very thin, in some places near their extremities almost as much so as writing 

 paper. The vertebra? and isehia present the same thin walls. The structure of these 

 walls is exceedingly dense. The special characters are as follows : 



Vertebrae. A dorso-lumbar is much compressed, but not keeled below ; the articular 

 extremities are expanded, and their feces slightly concave. An anterior caudal has a simi- 



