76 REPORT 1839. 



and broad, but is more particularly characterized by the lateral 

 expansion of its summit, the anterior angle of which is obliquely 

 truncated, presenting at that part a flattened surface. 



The vertical extent of the entire cervical vertebra here de- 

 scribed is 7 inches. The vertical diameter of the centrum 2| 

 inches ; its transverse diameter the same ; its antero-posterior 

 diameter 2^ inches. In its general proportions this vertebra has 

 most resemblance to the corresponding one of the PL macroce" 

 phalus, but it differs in the presence of the transverse processes, 

 and in the form, and especially the superior expansion of the 

 spine. 



The dorsal vertebrae are distinguishable by the correspond- 

 ingly great development of the transverse processes upon the 

 neurapophyses. 



The episternal bone of this species is figured in Mr. Hawkins's 

 26th Plate. It measures 1 6 inches and ^rd in transverse extent. 

 The arc of its anterior concavity, which is less deep than in PL 

 Maiv/cinsii, measures 8 inches. The lateral alee are slightly 

 convex externally, and terminate posteriorly at an acute point. 

 It is much flattened, thickest in the middle, from the internal 

 surface of which a longitudinal ridge is produced. 



The humerus of the same skeleton measures 14 inches long, 

 and 7 2 inches broad at its distal extremity. The anterior surface 

 is slightly concave, as in the PL macrocejihalus. The tuberosity 

 of its head is more raised than usual in the Plesiosauri, 



The dentary piece of the lower jaw contains the alveoli of 60 

 teeth ; the diameter of the base of the large anterior ones in the 

 expanded symphyseal portion equals frds of an inch. The 

 length of this dentary piece is 13 inches. The diameter of the 

 expanded symphysis 4 inches. 



In the collection of Miss Philpotts at Lyme Regis there is a 

 dentary bone which appears to be referrible to this species, but 

 it is smaller, measuring 13 inches in length and 3 inches across 

 the expanded symphysis ; it contains the alveoli of 27 — 27 = 54 

 teeth, of which the six anterior ones on each side are larger 

 than the rest, and occupy the first four inches of the bone on 

 each side. The projecting crown of one of these teeth measured 



1 inch 3 lines, and the breadth of its base 5| lines. 



A femur, supposed to belong to the same P/eslosaurus, mea- 

 sured 12 inches in length, and 6 in breadth at the distal end : 

 its anterior margin was slightly concave ; the shaft smooth, and 

 the extremities longitudinally striated : near the proximal end 

 {2~ inches below it) there is an oval muscular surface, measuring 



2 inches by 1 inch. 



Localities, — The remains of this species which I have exa- 



