1869.] MEETING OF THE AMERICAN ASSOCIATION. 331 



in the purity of its atmosphere, the clearness of its streams, and 

 its picturesque and extended views. The paper concluded with 

 some topographical details and with a list of Alpine plants. 



ON SOME NEW MOSOSAUEOID REPTILES FKOM THE 

 GREENSAND OF NEW JERSEY. 



By Prof. 0. C. Marsh. 



The striking difference between the reptilian fauna of the cre- 

 taceous period of Europe and the same period in America was 

 that in the former there were great numbers of remains of ichth- 

 yosauri and plesiosauri, while hardly a tooth or vertebra of the 

 mososauroids was to be found. In America the two former 

 kinds of reptiles appeared to be almost entirely wanting. One or 

 two specimens found here had been alleged to be icthyosauri or 

 plesiosauri, but further examination threw strong doubts on 

 the matter. To replace these forms, however, the mososauroids 

 were found in abundance. The aifinities of the mososauroids were 

 chiefly with the serpents rather than with other reptiles, although 

 they had certain other affinities with swarming reptiles. Prof. 

 Marsh produced some fossil remains of different specimens of 

 Mososauroids, showing the peculiar formation of the skull. These 

 reptiles appeared to have no hind limbs, although Cuvier thought 

 he had detected them. The specimens found in this country, 

 however, afforded no evidence of this. He called attention to 

 two new forms of the family — the Macrosaurus platyspondylus 

 and the Mosasaurus Copeanus — in which the articulation of the 

 lower jaw was one of the most interesting features. The larger 

 specimens of these animals showed that they must have been the 

 monarchs of the seas of those periods, and in appearance and size 

 not unlike the popular notion of the sea serpent, being sometimes 

 seventy-five feet long. 



Prof. Agassiz said that the examination of the Mososauroid 

 remains revealed much that was new to descriptive palaeontology. 

 He was not quite satisfied that the remains showed real serpent- 

 like affinities. The resemblances of the Mososauroids to serpents 

 he thought, were rather of the synthetic type than of affinity. 

 The articulation of the lower jaw, he thought, in no way corre- 

 sponded to that of serpents. 



