262 proceedings oe the geological society. [dec. 14, 



December 14, 1859. 



John Holmes Bass, Esq., 2 Picton Villas, Hollo way, was elected 

 a Fellow. 



The following communications were read : — 



1. Note on some Remains of Polyptychodon from Dorking. 

 By Prof. Owen, F.R.S., P.G.S., &c. 

 [Abstract.] 

 Referring to the genus of Saurians which he had founded, in 1841, 

 on certain large detached teeth from the Cretaceous beds of Kent and 

 Sussex, and which genus, in reference to the many-ridged or folded 

 character of the enamel of those teeth, he had proposed to call 

 Polyptychodon, Professor Owen noticed the successive discoveries 

 of portions of jaws, one showing the thecodont implantation of those 

 teeth, which, with the shape and proportions of the teeth, led him 

 to suspect the crocodilian affinities of Polyptychodon; and the sub- 

 sequent discovery of bones in a Lower Greensand quarry at Hythe, 

 which, on the hypothesis of their having belonged to Polyptychodon, 

 had led him to suspect that the genus conformed to the plesiosauroid 

 type. The fossils now exhibited by Mr. G. Cubitt consisted of part 

 of the cranium, with fragments of the upper and lower jaws and 

 teeth of the Polyptychoclon interruptus, from the Lower Chalk at 

 Dorking, and afforded further evidence of the plesiosauroid affinities 

 of the genus. 



The cranial fragment included the frontal, parietal, and mastoid 

 bones ; and at the overlapping suture between the frontal and pa- 

 rietal was situated a large oblique ' foramen parietale ' — a part not 

 present in the order Crocodilia, but characterizing the corresponding 

 region of the cranium in the Plesiosauroids, — the ' foramen parie- 

 tale ' being likewise present in many Lacertians, in the Dicyno- 

 donts, the Ichthyosaurs, and Labyrinthodonts. 



The temporal fossse were large, and met upon the upper part of 

 the parietal, with the intervention of a sharp and high ridge. The 

 nasal bone was narrow, and transversely convex above. Other par- 

 ticulars of the cranial structure were specified. 



Professor Owen further remarked, that, in a collection of fossils 

 from the Upper Greensand near Cambridge, now in the Woodwardian 

 Museum, and in another collection of fossils from the Greensand at 

 Kursk, Russia, submitted to the Professor's examination by their 

 discoverer, Colonel Kiprianoff, there were teeth of Polyptychoclon, 

 with plesiosauroid vertebrae of the same proportional magnitude. 

 In the Cambridge series, one of these vertebra?, from the cervical 

 region, presented the flattened articidar surfaces, and the single 

 transverse process for a simple-headed rib, on each side, closely 

 according with the plesiosauroid type. The length of this vertebra 

 was 4 inches 3 lines ; the breadth across the articular surface was 

 5 inches 3 lines ; the total breadth, including the transverse pro- 

 cesses, was 7 inches. 



