Manchester Memoirs, Vol. Iv. (191 1), A^^. 16. 



XVI. A Plesiosaurian Pectoral Girdle from the Lower 



Lias. 



By D. M. S. Watson, M.Sc 



Read November i^th, igio. Received for puhlicatioii January 24th, igii. 



The Manchester Museum contains a series of Liassic 

 reptiles, v/hich were collected by the late Charles Moore, 

 of Bath, but never incorporated in his collection ; these 

 reached the Museum through the good offices of Prof 

 Wm. Boyd Davvkins. The most important of them is a 

 specimen of a small plesiosaur from the Lower Lias of the 

 Bath district, most probably from Weston. This specimen 

 shews uncrushed and slightly separated all the bones ot 

 the pectoral girdle, the left humerus and ulna, the right 

 femur, and a long series of dorsal vertebrae. I at first 

 referred it to Plesiosaurus Hawkinsi, a species to which 

 the limb bones and vertebrae bear a very close resemblance. 

 A restoration, made both on paper and with the aid of 

 plasticene models, shewed, however, that the pectoral 

 girdle was of a somewhat different type. I, therefore, 

 made an attempt to develope one of the small fragments 

 of cervical vertebras which remained, and was able to 

 expose the whole of the under surface, which, in the 

 presence of a very marked haemal ridge, differs from the 

 corresponding bone of P. Hatvkinsi. I am not yet able to 

 make a definite identification of the species, but think it 

 is probably Plesiosaurus macrocephaliis. 



This view is supported by an examination I made 

 recently of the type specimen of P. brachycephaliis in the 



May igth, igii. 



