Geological Society of London. 183 



scription of Lord Cole's specimen of Plesiosarus macrocephalus, which 

 he compares with Mr Conybeare's Plesiosaurus Dolichodeiriis , by esta- 

 blishing an intermediate species, founded upon a specimen existing in 

 the British Museum, and termed by him Plesiosaurus Hawkinsii. Be- 

 sides tracing the analogies which connect these with each other, and 

 comparing them with the two great modifications of the saurian tribe, 

 the crocodiles and the lizards, Mr Owen presented his remarks on the 

 form of the Plesiosauvian vertebi-fe, founding them upon a general view of 

 the elements of which all vertebrse are constituted. 



" To the communications thus made to us, we may add Mr Owen's de- 

 termination of another animal, of which the remains brought from the 

 neighbourhood of Buenos Ayres, are among the manj' treasures of this 

 kind which we owe to Sir Woodbine Parish. This animal, of gigantic 

 dimensions, appears to have been allied to the Megatherium, but with 

 closer affinities to the Armadillos ; and it probably possessed the charac- 

 teristic armour, of which, in the Megatherium, the existence is perhaps 

 problematical. Mr Owen has termed it Glyptodon, from the furrowed shape 

 of its teeth. 



" In another communication Mr Owen endeavoured to account for the 

 dislocation of the tail of the Ichthj^osaurus at a certain point, which is 

 observable in many of the fossil skeletons of that animal. This circum- 

 stance, so remarkable from its general occurrence, and which Mr Owen 

 was the first to observe, he is disposed to account for, by supposing a 

 broad tegumcntary fin to have been attached to the tail for a portion of 

 its length, the position of which fin must, he conceives, have been vertical. 

 " I cannot close ray enumeration of the valuable contributions for which 

 we are indebted to Mr Owen, without remarking how well our anticipa- 

 tions have been verified, when, in awarding him the Wollaston medal last 

 year, we considered the labours which we thus distinguished as only the 

 beginning of an enlarged series of scientific successes ; and how well also 

 Mr Owen's own declaration, that he should lose no available time or op- 

 portunity which could be applied to palseontological research, has been 

 borne out by the services he has rendered that branch of our science. 



" In the remainder of my review of what has been done among us in 

 Palaeontology I must necessarily be very brief. I have already mentioned 

 the discovery of fossil fishes in the Bagshot sand. These fishes have sup- 

 plied three new genera, which Dr Buckland has distinguished and has 

 named Edaphndon, Passalodon, and Anieibodon ; of which the two first 

 offer combinations of the characters of bony and cartilaginous fishes. Mr 

 Stokes has given us his views of the structure of the animal to which be- 

 longed those fossils with which we arc so familiar under the name of Or- 

 thoceratites. He is of opinion, that these fossils, in their living condi- 

 tion, existed as a shell, enveloped within the body of the animal to which 

 they belonged. He has distinguished three genera of these shells, to 

 which he assigns the names Actinomiras, Ormoceras, and Huronia. The 

 Marquis of Northampton also has examined those minute spiral shells 



