1859.] OWEN POLYPTYCHODON FROM DORKING. 263 



One of the vertebrae from Kursk, belonging to the dorsal region, 

 showing the two venous foramina at the under surface, with other 

 plesiosauroid characters, measured 4 inches in length, and 5 inches 

 4 lines across the flat articular surface. No other teeth from the 

 Russian Greensand agreed in proportionate size with these vertebrae, 

 save those of Polyptychodon. Portions of large limb-bones, without 

 medullary cavity and of plesiosauroid shape, from the Greensand 

 beds of Cambridgeshire and Russia, were also believed by Professor 

 Owen to belong to the Polyptychodon ; and he was now led to refer 

 to the same genus the large Plesiosauroid paddle, from the Chalk of 

 Kent, the phalanges of which were figured in his ' History of British 

 Fossil Reptiles,' Part v. pi. 30, and in the ' Monograph on the Fossil 

 Reptilia of the Cretaceous Formations ' (Pakeont. Soc), pi. 17. Thus 

 the evidence at present obtained respecting the huge but hitherto 

 problematical carnivorous Saurian of the Cretaceous period, seemed 

 to prove it to be a marine one — the rival and contemporary of the 

 equally huge Maestricht lizard. But whilst the Mosasaurus, by its 

 vertebral, palatal, and dental characters, seemed to foreshadow the 

 saurian type to follow, the Polyptychodon adhered more closely to 

 the prevailing type of the sea-lizards of the great geological epoch 

 then drawing to its close. 



Professor Owen also exhibited drawings showing the mode and 

 degree of use or abrasion to which the teeth of Polyptychodon had 

 been subject. 



One of these teeth, in the collection of "W. Harris, Esq., F.G.S., 

 from a chalky deposit with greenish granules, in a tunnel of the 

 railway near Frome, Somerset, showed the apical half of the crown 

 smoothly worn away, and presenting a flattened surface continued 

 obliquely a little way upon one side of the crown. 



Another tooth, from the Cambridge Greensand, measuring 1 -J- inch 

 across the base, showed, with abrasion of a great part of the crown, 

 a smooth, slightly concave channel extending from the crown to the 

 fang, and apparently formed by the gnashing action of an opposite 

 large tooth. 



2. On the Discovery of some Fossil Remains near Baiiia in South 

 A.Mi.kicA. By S. Allpokt, Esq. 



[Communicated by John Morris, Esq., F.G.S.] 

 [Plates XIV.-X\ ll.| 



On referring to a map of Baiiia, it will be seen that a line ofhilLa 

 runs from the Point of St. Antonio in a north-easterly direction. 

 They form for some distance steep rockj cliffs, skirting the Bay, and 

 continue in the same direction for several miles. Tln\ also form 

 the seaward exposed edge of an elevated range of country, and 

 l>n sent a steep slope to the X.W. ; and are everywhere covered by 

 red Loam or sand, excepl where exposed to the action of thi 

 Tlie.se are gneisso86 rocks, usually exhibiting distinct lines of strati- 



