480 



PROF. W. J. SOLLAS ON PLESIOSAURTJS 



The remaining measurements are given in the appended Table 



(p- 477 )- 



Geological Horizon. — Associated with this specimen, which came 

 from the Lias of Bitton, are some Ammonites and Bhynchonellce, 

 which Mr. Whidborne regards as A. Conybeari and R. variabilis ; 

 hence he refers it to the A.-Bucklandi zone. 



In concluding this paper, I have to offer my best thanks to 

 Mr. Etheridge and Dr. Henry Woodward for the kind assistance 

 they have given me in many ways ; to Mr. Whidborne I am espe- 

 cially indebted for much useful help, and particularly for his care 

 and assiduity m drawing up the appended list of species, with their 

 geological positions, many of which have been determined by his 

 own personal examination of the original types. 



EXPLANATION OF PLATES XXIII. & XXIV. 

 Plate XXIII. 



Plesiosaurus Conybeari. 



Fig. 1. Ventral aspect of the skeleton. One twelfth nat. size. 



2. Dorsal aspect, showing the vertebral column from the thirty-seventh 



(xxxvn) to the sixty-third (lxiii) vertebrae. About one eleventh 

 nat. size. 



3. Diagrammatic restoration of the pectoral girdle. One eighth nat. size. 



4. Diagrammatic restoration of the pelvic girdle, the ilia not being repre- 



sented. One eighth nat. size. 



Plate XXIV. 



Fig. 1. Skull of P. Conybeari, left side. About one fourth nat. size. 



2. Skeleton of P. brachycephalus, Owen. About one twelfth nat. size. 



DlSCTTSSIOK. 



Prof. Seeley said that without an inspection of the evidence 

 he was not in a position to criticise this elaborate paper ; but it 

 gave evidence of painstaking research of no ordinary kind, and he 

 congratulated the author upon what he had put forward. He 

 thought, however, that a part of the information was not entirely 

 new. Still the species, he fully believed, was a new one, as several 

 of the characteristics are not found in any other described Plesio- 

 saur. He had an impression that the palatal foramina described 

 by Prof. Sollas were shown in the species described by Mr. Stutch- 

 bury fourteen years ago ; and he believed they had been excavated 

 after that description had been drawn up. As to the Lacertilian 

 affinities of Plesiosaurus, he was unable himself, so far as he had 

 seen, to recognize any of importance. In some respects it had 

 affinities with Ichthyosaurs, Dinosaurs, and Crocodiles ; so he thought 

 the Lacertilian affinities could not be pressed. Though he dif- 

 fered in some details, he thought the paper, as a whole, was done 

 extremely well. 



