PLESIOSATTE.IDJE. 275 



skeleton No. R. 1337 of P. rostratus, but is of larger size ; 

 in which respect it agrees with the dcrsals of the next 

 specimen. The costal facets are distinctly double and 

 pedunculated, in which respect it differs widely from the 

 later cervicals of the type and of No. 28318 of P. rostratus. 

 The terminal faces are distinctly cupped, with well bevelled 

 edges, while the haemal ridge is much more prominent 

 than in No. 28318, and has very deep pits on either 

 side. The general characters of the haemal surface accord 

 with those of the late cervical of P. rostratus figured by 

 Owen in his ' Liassic Reptilia,' pi. xi. fig. 2, in conjunction 

 with the 16th and 17th as the 18th, bat which, as men- 

 tioned above, is really much later in the series. The 

 resemblance of this specimen to the 30th and 31st vertebrae 

 of P. rostratus, No. R. 1337, indicates that those vertebrae 

 are cervical. No history. 



R. 1368. A mass containing four imperfect cervical and three 

 " pectoral " vertebrae ; from the Lower Lias, locality 

 unknown. The cervicals, which are from the middle part 

 of the series, agree with those of P. rostratus in their 

 extremely short neural spines, but differ by the more 

 depressed form of the centrum, and the more prominent 

 haemal ridge, which has no distinct pit on either side, 

 The costal facets show a double articulation, although the 

 two branches are closely pressed together. The " pectorals " 

 are larger than in the type of P. rostratus, and the dorsals 

 have the terminal faces of the centra more heart-shaped. 

 The dimensions of one of these centra are : — length 0,0 i 8 

 (1-89 inches), height 0,071 (2-8 inches), width (about) 

 0,089 (3-52 inches). No history. 



R. 1315. Slab showing the ventral aspect of the middle portion of 

 a skeleton provisionally regarded as that of a young indi- 

 vidual of the present species ; from tne Lower Lias of 

 Keynsham, near Bath. The pectoral girdle is shown in 

 a perfect condition ; in advance of this are 2G cervical 

 vertebrae with very prominent double costal facets, i<> 

 which the ribs were attached only by cartilage. Hie 

 proximal portion of the left pectoral limb is in its natural 

 position, and there are three del ached phalangeals. Pos- 

 teriorly to the coracoids a few dorsal vertebra, ribs, and 

 some of the abdominal rib- are apparent. The cervical 

 vertebrae have shorl centra and the posterior ones closelj 



