PLIOSATJBUS. IT 



The scapula is a triradiate bone. The posterior ramus, which unites with the coracoid 

 and forms the anterior half of the glenoid cavity, is triangular in section, the inner 

 augle being sharp, the outer more rounded, while the lower forms a tectiform ridge, 

 becoming sharper as it is traced forwards to the anterior angle of the bone and dividing 

 the ventral from the outer surface of the dorsal ramus. The articular end is much 

 thickened and bears the surfaces for union with the coracoid and for the glenoid 

 cavity : the former is triangular in outline and makes an angle of about 100° with 

 the latter, which is longer and slightly concave. The dorsal ramus is broad and flat, 

 but no specimen showing its exact form is known. The anterior (ventral) ramus is not 

 known in any specimen belonging to this species, but probably it was very similar to 

 that of the scapula of a Pliosaur from the Kimmeridge Clay (Brit. Mus. E. 287), which 

 in other respects it resembles. In this it is greatly expanded at its inner end and is 

 broadly rounded. The scapula is also similar to that of Pelonevstes, except that the 

 expansion of the ventral ramus is considerably greater. Probably the ventral rami 

 did not quite meet in the middle line, but had an interclavicle wedged between them 

 as in Peloneustes. 



The coracoid (text-fig. 5) is here described from an isolated complete example about 

 the same size as that belonging to the skeleton above noticed. The greater part of the 

 bone is very thin, the thickened portion lying between the surfaces for the scapula and 

 glenoid cavity on the outer side and the deepened portion of the median symphysis on 

 the inner side. From before backwards the symphysial border is nearly straight. An- 

 teriorly, as mentioned above, it is much deepened for a short distance, giving rise to 

 a strong convexity on the visceral face and a slight concavity below (text-fig. 5, sym.). 

 Anteriorly the middle portion of the bone is prolonged forwards {a.p.), the outer side of 

 the prolongation being the thin anterior edge of the bone which extends to the facet 

 for the scapula ; there is no evidence that the anterior prolongation was in contact 

 with the ventral ramus of the scapula ; it was fringed with cartilage, at least on its 

 anterior and inner sides. The outer border of the bone behind the solenoid cavity 

 is concave, the hinder convex or irregular ; there is no very well-marked postero- 

 external process. The surface for union with the scapula is triangular and much 

 roughened with ridges ; the base of the triangle marks the line of union with the 

 glenoid surface, which is very large and in the form of half an oval ; it is gently 

 concave, and its surface is smoother than that for the scapula. The angle between 

 the glenoid and scapular surfaces is more obtuse than in Cryptocleidvs, and measures 

 about 150°. The posterior border of the coracoid is grooved and evidently was 

 fringed with cartilage in life. 



The clavicular arch is unknown in the genus : probably it was closely similar to 

 that found in Peloneustes (p. 56). 



Fore Limb (text-fig. 6, B). — Unfortunately no very complete specimen of the fore 

 paddle is available for description, but since, so far as it is known, it is closely similar 



PART II. D 



