GEOLOGY. 253 



Stated that the elevation of the bottom of Behring's Straits, 180 

 feet, would make dry land between Asia and America, but that a 

 deep ocean valley extended south-west from Plover Bay, just west 

 of the Straits, along the Kamschatka coast. 



REPTILIAN REMAINS. BY PROFESSOR COPE. 



The fossil which Professor Cope exhibited was the almost 

 perfect cranium of a mosasauroid reptile, the Clidastes propy- 

 thon. He explained various peculiarities of its structure, as 

 the movable articulation of certain of the mandibular pieces 

 on each other, the suspension of the os-quadratum at the ex- 

 tremity of a cylinder composed of the opistholic, etc., and other 

 peculiarities. He also explained, from specimens, the charac- 

 ters of a large new plesiosauroid, from Kansas, discov^ered by 

 William E. Webb, of Topeka, which possessed deeply biconcave 

 vertebrae, and anchylosed neural aix-hes, with the zygapophyses 

 directed after the manner usual among vertebrates. The former 

 was thus shown to belong to the true sauropterygia, and not to 

 the streptosauria, of which Elas mosaurus was the type. Sev- 

 eral distal caudals were anchylosed, without chevron bones, 

 and of depressed form, while proximal caudals had anchylosed 

 diapophyses and distinct chevron bones. The Ibrm was regarded 

 as new, and called Polycotylusa latipinnis, from the great relative 

 stoutness of the paddle. He also gave an account of the discov- 

 ery, by Dr. Samuel Lockwood, of Keyport, of a fragment of a 

 large dinosaur, in the clay which underlies immediately the clay 

 marls below the lower green-sand bed in Monmouth Count}'', 

 N. J. The piece was the extremities of the tibia and libula, with 

 astragalo-calcaneum anchjiosed to the former ; in length, about 

 16 inches; distal width, 14. The confluence of the tirst series 

 of tarsal bones with each other, and with the tibia, he regarded 

 as a most interesting peculiarity, and one only met with else- 

 where in the reptile compsognathus, and in birds. He therefore 

 referred the animal to the order symphypoda, near to compsogna- 

 thus wagra. Tlie extremity of the libula was free from, and 

 received into, a cavity of the astragalo-calcaneum, and demon- 

 strated what the sj^eaker had already asserted, that the fibula of 

 iguanodon and hadrosaurus had been inverted by their describers. 

 The medullary cavity was filled with open cancellous tissue. The 

 species, which was one-half larger than the type specimen of 

 Hadrosaurus foulkii, he named Orntliotai\sus immanis. — Proc. Am. 

 Phil. Soc, xi., 117. 



PAPERS READ AT THE MEETING OF THE AMERICAN ASSOCIA- 

 TION. 



Prof. O. C. Marsh read a paper upon the "Discovery of the Re- 



noii ~^ 



22 



mains of the Horse among the Ancient Ruins of Central America." 



