GEOLOGY. 255 



the shore of a great lake, and that the animals were mired when 

 they went down to the water to drink. 



At the close of Prof. Marsh's address, Prof. Agassiz made a few 

 interesting remarks on the jDOssibility of determining genuine 

 affinities from fragmentary fossil remains, after which he read a 

 paper on the " Homologies of the Paltechinidse," partially pre- 

 pared by his son, Alexander E. R. Agassiz. 



Mosasauroid Reptiles. — Professor O. C, Marsh read a paper on 

 *'Some new Mosasauroid Reptiles from the Green-sand of New Jer- 

 sey." The striking difference between the reptilian fauna of the 

 cretaceous period of Europe and tiie same period in America was, 

 tliat in the former there were great numbers of remains of ichthyo- 

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

 mosasauroids 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 ichthyosauri, 

 or plesiosauri ; but further examination throw strong doubts 

 on the mat^r. To replace these forms, however, the mosasau- 

 roids were tound in abundance. The atlinities of the mosasauroids 

 were chiefly with the serpents ratluir than with other reptiles, al- 

 though they had certain other affinities with swarming reptiles. 

 Professor Mai'sh produced some fossil remains of different speci- 

 mens of mosasauroids, 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 atten- 

 tion to two new forms of the family, — the Macrosaurus platyspon- 

 ihdus and the Mosasaurus copeanus, — in which the articulation of 

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

 larger specimens of these animals showed that they must have 

 been the monarehs of the seas of those periods, and in appearance 

 and size not unlike the popular notion of the sea-serpent, being 

 sometimes 75 feet long. 



Professor Agassiz said that the examination of the mosasauroid 

 remains reveals much that was new to descriptive palseontologJ^ 

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

 like affinities. The resemblances of the mosasauroids to serpents, 

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

 articulation of the lower jaw, he thought, in no way corresponded 

 to that of serpents. 



Extinct Cetacea. — Professor Cope's observations embraced a 

 description of the characters of a very large representative of the 

 dujron": of the modern East Indian seas, which was found in a 

 bed, either miocene or eocene, in New Jersey. It was double 

 the size of the existing dugong, and was interesting as adding to 

 the series of Asiatic and African forms characteristic of American 

 miocenes. Another tyi3e was regarded as remotely allied to 

 squalodon ; but it was indentulous, and furnished with a broad, 

 shallow alveolus, either that left after shedding a tooth, or that 

 adapted to a broad, obtuse tooth. It constituted a remarkable 

 new genus, which was called Anopolonassa forcipata. It was 

 found in postpliocene beds, near Savannah. He also exhibited 



