Mr. H. G. Seeley on a neio Species o/" Plesiosaurus. 181 



haud albo terminatis, et rectricibus exterioribus brunneis pogonio 

 externo isabellino marginato, haud albis, distinguenda. 



Hob. North-east Africa [Brehm^ Heuglin) , Palestine ( 2?-/s- 

 tram), Caucasus {MenetrUs), ? Persia {DeJiUj)jn)^ Turkestan 

 {Dode)j Cashmere [Jerdon), North-west India {Blyth^ Hume). 



XX. — On a neio Species of Plesiosaurus from the Portland 

 Limestone*. By Haery G. Seeley, F.G.S., St. John's 

 College, Cambridge. 



When the Index to the Reptilian Remains from the Secondary 

 strata preserved in the Woodwardian Museum was written, an 

 examination of many examples of Plesiosauria had shown 

 that, with perfect specimens, good characters were available 

 by which the overgrown genus Plesiosaurus might be sepa- 

 rated into natm-al genera. Hence, when recording the few 

 remains from the Portland Oolite (p. 91), finding the charac- 

 ters of Pliosaurus blended to some extent with those of Plesio- 

 saurus^ I did not feel it easy to volunteer an opinion on generic 

 affinities. 



Since then. Prof. Owen's memoir in the Palgeontographical 

 Society's volume (1869) on Pliosaurus portlandlcus has been 

 published ; and in the absence of associated vertebrae showing 

 the distinctive Pliosaurian characters of the neural arch and 

 centrum, I cannot but feel less confidence than Prof. Owen 

 expresses in regarding the paddle there figured as the type of 

 the Pliosurian hind limb. In some large-headed Plesiosaurs, 

 such as Plesiosaurus macrocephalus (Owen), the tibia and 

 fibula, and ulna and radius, become shorter than in small- 

 headed species ; and although the tarsus in Prof. Owen's 

 fossil is very similar to that of Pliosam's from the Kimmeridge 

 Clay, the femur is more like Plesiosaurus ; and it is not im- 

 possible that the Portland specimen may typify a new genus. 

 All the limb-bones from the Portland Limestone, so far as 

 known to me, are pliosauroid, while all the vertebrge are 

 plesiosauroid. 



Therefore with some interest we received from an inde- 

 fatigable correspondent, Mr. W. R. Brodie, some vertebra? 

 which demonstrate, as conclusively as vertebra; can, the exist- 

 ence in the Portland Limestone of a ncAV species of Plesio- 

 saurus. They were found by Mr. Brodie at the Winspit 



* Communicated bv the author, having been read before the Cambridge 

 Philosophical Society, May 30, 1870. 



