230 Memervs — Dr. Winkler on Plesiosaurus. 



dorsal and lumbar, 2 sacral, and 26 caudal. The bones of the 

 right fore-limb are nearly all in their natural position, the humerus 

 is well preserved, the ulna and radius, short and broad, are succeeded 

 by the proximal row of the carpus, which, according to Dr. Winkler, 

 consists oi five bones; the smallest or pisiform, of triangular form, is 

 situated a little without and below the radius. Cuvier stated there 

 were only four bones in the first row, and figured but three in the 

 Ossements fossiles (tome v. p. 483, pi. xxxii. fig. 1). 



Prof. Owen describes the carpus as consisting *' of a double row 

 of flat rounded discs, — the largest at the radial side of the wrist ; 

 the ulnar or hinder side appearing to have more unossified matter " 

 (Palaeontology, p. 248). Prof. Huxley states "there are six rounded 

 carpal bones, arranged in two rows" (Manual, p. 214). 



The Plesiosauria or Sauropterygia are essentially Mesozoic reptiles, 

 but the genera have a more or less restricted range throughout that 

 period. In the Trias are found NotJiosaurus, Pistosaurus. ConcMo- 

 saurus, Siniosaurus, and Flacodus, while Pliosaurus and Plesiosaurus 

 are Post-Triassic, the former genus being chiefly confined to the 

 Kimmeridge and Oxford Clays, the latter ranging from the Lias to 

 the Chalk inclusive, and comprising many species. The first described 

 species, P. dolichodeirus, is remarkable for the long neck and the small- 

 ness of the head in proportion to the body ; P. macrocefhalus, Conyb., 

 has the head larger and the neck stronger; the P. Hawkinsi, Ow., has 

 the snout shorter and more narrow; besides these three species there 

 also occur in the Lias the P. arcuatus, Ow., P. brachycephaliis, Ow., 

 P. macromus, P. rugosus, P. subtrigonus, Ow., P. Cramptoni, Baily, 

 P. Etheridgii, Huxl. In the Lower and Middle Oolite occur P. carin- 

 atus, pentagonus, and trigonus, Cuv., founded upon vertebrae, P. erra- 

 ticus, Phil., P. trochanterius, Ow., P. eurymerus, Oxoniensis, plicatus, 

 Phil., and in the Upper Oolite P. affinis, dcedicomiis ellipsospondylus, 

 trochanterius, Ow., P. carinatus, plicatus, validus, Phil., and P. hrachy- 

 spondylus, Ow., which, according to Dr. Winkler, is the same as P. 

 recentior and P. giganteus, Conyb. The Plesiosaurs lived during 

 the Cretaceous epoch ; three species have been described by Prof. 

 Owen, the P. Bernardi, P. constrictus, and P. pachycomiis ; and Dr. 

 Harlan has also indicated a species from the Greensand of New 

 Jersey. J. M. 



nected "with the sternum, or if such connexion existed it cannot now be traced, it 

 becomes difficult to distinguish between dorsal and cervical vertebrae, and one is 

 obliged to have some other method of separating the two, differing from that already 

 adopted. Now, in these animals, the neurocentral suture persists for a considerable 

 period, if not throughout life ; and the surfaces for the articulation of the cervical 

 ribs, which are at first altogether below the neurocentral sutures, gradually rise, in the 

 posterior part of the neck, until they are first cut by, and then rise above, the suture. 

 It is very convenient, and harmonizes very well with some facts in the structure of 

 the Grocodilia, to take the last of the vertebrae, in which the costal articular surface 

 is cut by the neurocentral suture, as the last of the cervical series" (Manual of the 

 Anatomy of Vertebrated Animals, p. 209). 



