196 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 7, 



EXPLANATION OF PLATE IIL 

 (All the figures are of the natural size.) 



Fig. 1. Portion of lower jaw with the three true molars, ml, m2, m2>, from 

 the outside. 



Fig. 2. Crowns of the same teeth, from the inside. 



Fig. 3. Grinding surface of the same teeth : /, outer cusp or di\ision of the lobes 

 of the first true molar ; a, h, c, d, e, the five internal accessory basal 

 cusps of the internal di\'isions of the same tooth ]f,/\ the outer divi- 

 sions of the two anterior lobes of the last molar ; 5', the outer division 

 of the third lobe of the same tooth. 

 This specimen is from the Upper Eocene clay of the Isle of Wight, in the col- 

 lection of Dr. Wright of Cheltenham. 



Fig. 4. Part of the upper jaw, showing the working surface of the right incisors, 

 canine, and three anterior premolars, as in their natural position. 



4 a. Outside view of the third premolar of the same specimen. 

 Fig. 5. Portion of lower jaw, with the last true molar. 



5 a. Grinding surface of the same molar. 



These specimens are from the Upper Eocene sands of Hordwell, Hants, and are 

 in the British Museum. 



2. On the Fossil Vertebra of a Serpent (Laophis crotaloides, 

 Ow.) discovered by Capt. Spratt, R.N., in a Tertiary Forma- 

 tion at Salonica*. By Prof. Owen, F.R.S., F.G.S. &c. 



[Plate IV.] 



The characters for distinguishing and determining the fossil remains 

 of Serpents are deemed, I believe, by most palaeontologists to be less 

 salient and satisfactory than in those of other reptiles. I have found, 

 however, in the course of comparisons called for by the discovery of 

 Ophidiolites in our own tertiary strata, more differentiating characters 

 in Ophidian vertebrae than the works on comparative anatomy gave 

 promise of; and no palaeontologist would find a difficulty in distin- 

 guishing the vertebra of an eocene Palceophis (PI. IV. fig. 1), e.g. 

 from that of any known existing Ophidian, provided the neural arch 

 (w, z) were entire. 



For the nomenclature of the parts and processes of an Ophidian 

 vertebra, and for their chief modifications in existing Serpents, I must 

 refer to my "History of British Fossil Reptilesf," pp- 135-139, 

 Ophidiay plates 2 and 3. It will there be seen that in the genera 

 Python (figs. 5 and 6), Boa, Eryx, Coluber (fig. 7), Deirodon, and 

 Hydrus, the hypapophysis (Ji) subsides into a ridge, or a short sub- 

 compressed tubercle, in the vertebrae situated behind the anterior 

 third or fourth part of the trunk ; but that in Crotalus (fig. 4), Vi- 

 pera, and Natrix the hypapophysis, A, is continued, with more or 

 less diminution of relative length, from all the vertebrae supporting 

 free ribs. 



In all the fossil vertebrae of the Serpent from Salonica, thirteen in 

 number, submitted to my examination, the hypapophysis (figs. 2 

 and 3, A), where entire, is developed, of equal length and similar form, 



* See above, p. 183. 



t See also Monograph of the Eocene Reptiles, Palaeont. Soc. 1850, plates 13 

 and 14. 



