252 



SATJE0PTERYGJA. 



small or not very large. Vertebrae with the arches and cervical 

 ribs firmly attached to the centrum, but with the suture not oblite- 

 rated ; zygapophyses slightly curved, and zygosphenes not strongly 

 developed. Cervicals usually with moderately long centra, generally 

 having double costal facets (fig. 78), and the terminal faces trans- 

 versely ellipsoidal and more or less cupped. Dorsals without 

 distinct forward overhang of centrum. Pectoral girdle (fig. 77) 

 with the scapulae small, and widely separated in the middle line, 

 where they rest upon the omosternum; ventral plate of scapula 

 narrow, and set at right angles to, and not larger than, the dorsal, 

 which gives off a long projection ; coracoids long and narrow, with 

 a median anterior production ; coracoidal foramen large and open 

 anteriorly ; omosternum of moderate size, consisting of two elements, 



Fig. 78. 



Plesiosaurus homalospondyhis. — Left lateral and posterior aspects of a late cer- 

 vical vertebra ; from the Upper Lias of Curcy. \. Letters as in fig. 69, 

 p. 225. 



in shape like a subequilateral triangle, with a narrow and deep 

 anterior notch. In pelvis ischia moderately elongated ; pubes with 

 distinct acetabular production. Humerus either rather shorter than 

 or nearly equal in length with the femur, and articulating distally 

 only with the radius and ulna (fig. 79), which are more or less 

 elongated, and separated by a distinct interval; ulna and fibula 

 reniform, the former more slender and sometimes longer than the 

 latter. 



