Cope.] J-'^ [Eebruaryl9,1869. 



the present animal, where that distance is only twice as great as that 

 between the first and second molars. 



Prof. Cope described several points of novelty and import- 

 ance in the memoir on the Fossil Batracliia of North America, 

 which the Society is publishing in Part 1 of Vol. XIY. of its 

 Transactions ; and expressed a desire that the Society should 

 permit him to illustrate the memoir with additional plates. 



He pointed out that all the tortoises of the Cretaceous yet discovered 

 were fresh water forms, many allied to Chelydra, and that there were no 

 extinct land tortoises or Testudinidae in North America, the species from 

 the Western Territories referred hitherto to Testudo being in fact Eniy- 

 didge. He called attention to the peculiar characters of the Mosasaurs 

 and of the Streptosauria, as not having been previously pointed out, and 

 stated there were eleven species of the first named group known to him 

 from North America. One of these, M. depressus Cope, common in New 

 Jersey, is defined by the transverse ovate form of the vertebral centra 

 throughout the column, and the presence of a prominent rib of the outer 

 face of the quadrate bone, throwing the meatal pit inward, and not 

 reaching the proximal articular face. 



He mentioned also the modifications of form in the Dinosaurian skele- 

 ton, by which an approach to the Birds was indicated. Thus the ilium 

 from a vertical, assumed a transverse position, the acetabulum being 

 thrown upward and forward, while the great size and inferior and pos- 

 terior position of the other pelvic elements transformed the weight of 

 the viscera posteriorly, to beneath the support. The consequence of this 

 was the inclosure of a longer series of vertebrae as sacral, derived from 

 the lumbar series, and the support of the body by a powerful hind limb, 

 more nearly beneath the centre of gravity than ^n other types of reptiles. 



-An additional approximation to the birds was seen in the hind limbs. 

 The head of the femur was transverse to the condyles, and the crest of 

 the ilium furnished with a very elevated crest. In the more quadrupedal 

 forms as Iguanodon and Hadrosaurus the crest was much curved out- 

 wards, while in the biped types as Laelaps and Pcecilopleurum the crest 

 projected more forward. In the latter also the astrogalus embraced the 

 tibia in the closest manner, and presented to the foot at a remarkable angle. 

 In Compsognathus this element had united with the tibia as in birds. 

 The latter and Stenopelix Myo, he stated to be the best preserved injpelvic 

 characters. He stated that these affinities had been explained by him at 

 a meeting of the Academy of Natural Sciences of Philadelphia, in Feb., 

 1867, and had since been confirmed by other authors. 



Nominations Nos. 622 and 623, and new nominations Nos. 

 624, 625, 626 were read. 



And the Society was adjourned. 



