AND AVES OF NORTH AMERICA. 



169 



P T E Bt O S A D K t 4 : 

 EtHABDOPELIX, Cope. 



This genus and species are based upon numerous bones, mostly scattered, occurring in 

 a bed of very hard indurated siliceous clay, of a, dark gray color, which intervenes between 

 the usual redder strata in the Triassic or Jurassic sand-stone of the Atlantic slope, at 

 Gwynnedd, Montgomery County, Pa. In the red slaty layers occur impressions of narrow 

 leaves, worm tracks and bo.rings, scales of Ganoid Fishes, and rain-drop and ripple-marks. 



The hones, which are very abundant, are indicated by thin black mineral layers which 

 do not effervesce in acid, and whose coloring matter, perhaps a phosphate of iron, with 

 some carbonaceous matter, becomes blue on exposure to the weather, and is finally alto- 

 gether dissolved or weathered away. In the cavities of many of the long bones may be 

 observed a deposit of carbonate of lime. All appear to have been more or less flattened, 

 and their walls are much attenuated. This, with the hardness of tin; matrix, has ren- 

 dered their preservation difficult, and their identification requires much care; and though 

 1 have had them under careful observation, in the Museum of the Academy for three years, 

 I am hardly satisfied as to their affinities, ft would appear as though quite a, number of 

 individuals had mingled their remains in the accumulation, and perhaps more than 

 One spceies. 



The specimens were discovered by the late President of the Academy, Dr. Isaac Lea, 

 who found considerable masses of the rock containing them, showing an accumulation 

 which has occupied some time in formation. 



There are sufficient reasons why these bones cannot be referred to a Lacertilian. They 

 are, first, the presence of the Pterosaurian confluent ulna and radius, or tibia and fibula; 

 second, the existence of subspatuliform, distally free pubic elements; the apparently com- 

 plete pneumaticity of the long bones; the curvature and lack of condyles of most of the 

 latter. 



The centra of the vertebrae an- much depressed in part of the column, thus agreeing 

 With Pterosauria and some Lacertilia. Elongate cervical vertebrae arc also characteristic 

 of the Pterosauria, but exist likewise in the genera Compsognathus and Dolichosaurus. 

 The centra of the vertebrae have projected considerably beyond the neural arch, and the 

 latter has supported an elevated longitudinal neural spine, both characters of Pterosauria. 

 Where the hypapophysis has existed it has been at the anterior extremity, as in Crocodilia 

 and Pterodactyles, and not behind, as in Iguania. 



The remains do not pertain to Batrachia, for the following reasons : The creature was 

 of an elongate vertebral axis, and possessed none of the peculiar elements of the Anura; 



AMERICA. nilLO. soc. — vol. xiv. 43 



