NATURAL SCIENCES OF PHILADELPHIA. 549 



Marshii, Marcou, is not 0. Marshii, Sow., and therefore the name 0. subovata, 

 Shumard, is the real name of the species. Gryphcea Tucumcarii, M., is at 

 least as nearly related to the typical specimens of G. Pitcherii, Morton, now in 

 the Museum of the Academy, as the forms referred to Pitcherii by Marcou, 

 and known to geologists as var. navis. The specimen from the plains of 

 Kiamesha, mentioned by Morton, is more nearly of the shfpe of Tucumcarii. 

 than the one figured, but no palaeontologist would hesitate for a moment in 

 pronouncing thm identical. 



In regard to the real position of these species, Dr. Shumard, in Marcy's Re- 

 port on the Red River of Louisiana, places 0. subovata, on the same horizon 

 with G. Pitcherii and Ammonites vespertinus, both of which species are, mother 

 parts of the United States, found associated with species that are everywhere 

 characteristic of the chalk, such as Baculites anceps, Gryphcea vesicularis, 

 Ostrea larva, Exogyra Matheroniana, of D'Orbigny, (or E. Texana, Roemer,) 

 Nautilus Dekayi and other species, not only found in the United States, but in 

 Europe, Chili and India, and never found outside of the Upper Chalk of Eng- 

 lish authors, the Senonien of the French. 



Mr. Gabb did not pretend to deny the existence of the older members of 

 the cretaceous formation in North America, but said, that outside of the 

 evidence in "Geology of North America," founded only on the doubtful re- 

 cognition of two or three species of Ammonites from weathered fragments, all 

 the testimony yet collected tends to prove the existence only of the Upper 

 Chalk, unless, perhaps, some of the lower beds (Nos. 1 and 2) of Nebraska 

 may prove, as he thinks probable, to belong to the Lower Chalk of the Eng- 

 lish, the Turonien of continental writers. Still the evidence is only negative. 

 True, the beds of New Jersey cannot be distinguished lithologically from the 

 green sand of England and France, but even Prof. Marcou would not now 

 have the temerity to call them upper green sand or even "Turonien " in face 

 of the palasontological evidence to the contrary ; and yet, lithological evidence 

 is among the strongest brought to bear on his Jurassic and Triassic of the 

 West. That Jurassic and Triassic rocks do exist on this continent is now 

 beyond doubt, but that Jurassic and Triassic, is not the Jurassic and Triassic 

 of Marcou. That Ostrea Marshii has been found in the far West, associated 

 with Ammonites cordatus, it is no evidence that the 0. Marshii of Prof. Marcou 

 is the 0. Marshii, Sow. 



In conclusion, he remarked that in the above opinions he was upheld by 

 every American geologist who has investigated the subject. 



Mr. Cope read the following list of the recent species of Emydosaurian rep- 

 tiles represented in the museum of the Academy. 



alliqatoridjE. Crocodilus palustris, 



Alligator Mississippiensis, Crocodilus porosus, 



Jacare sclerops, Crocodilus vulgaris, 



Jacare fissipes, Crocodilus Americanus, 



Jacare vallifrons. Mecistops leptorhynchus, 



crocodilid^e Mecistops bathyrhynchus, 



Osteolaemus tetraspis Gavialis Gangeticus. 



In all, twelve species, represented by thirty-eight specimens. 



Osteolaemds, Cope, was characterized as a genus of Crocodiles presenting 

 several points of analogy to the Alligators. The nasal bones were prolonged 

 anteriorly, and uniting with the short spine of the intermaxillary, divided the 

 external nasal orifice, as in the genus Alligator. The eyelids were entirely os- 

 seous, as in Caiman. There was no transverse bony ridge between the orbits. 

 The dermal plates upon the tail, extremities, and thorax, were more or less com- 

 pletely ossified ; upon the gular region the ossification was most complete, the 

 shields having a coarse sutural articulation. The digits of the posterior ex- 

 tremity were very slightly webbed. Cervical plates distinct from the dorsal. 



I860.] 38 



