io8o 



CLASS REPTILIA. 



was short, and the cervical vertebras have comparatively short and 

 distinctly cupped subcylindrical centra, carrying double costal 

 facets ; while the arches and cervical ribs were firmly articulated to 

 the centra. In the pectoral girdle the scapulas and coracoids were 

 of the general type of those of Plesiosaurus ; but the clavicular 



..om 



Fig. 1002. — Anterior part of the pectoral girdle of Peloneustes philarchus ', from the Oxford 

 Clay. Reduced, om, Interclavicle ; sc, Scapula ; p. cor, Ventral plate of do. The ventral 

 aspect is shown. 



arch was greatly elongated transversely, and was probably over- 

 lapped by the scapulae. The humerus was longer or shorter than 

 the femur, and articulated only with the radius and ulna, which 

 were considerably elongated, and separated by a distinct interval. 

 This genus is represented in the Lower Lias by T. megacephalus 

 and T. arcuatus, and in the Upper Lias by the gigantic T. Cramp- 

 toni, which attained a length of some twenty feet. 

 The type species, only known by detached teeth 

 and vertebrae, occurs in the Great Oolite of the 

 Continent ; while T. indicus (fig. 996, b) is found 

 in the Upper Jurassic of India. 



In the genus Peloneustes, of the Oxford and 

 Kimeridge Clays, the coracoids (fig. tooi) do not 

 appear to have been produced anteriorly in the 

 middle line ; while the scapulae have their ventral 

 surface broad and flat, and the dorsal surface re- 

 duced (fig. 1002). The same figure also shows the 

 extremely small size of the interclavicle. The ischia 

 were very long. The mandibular symphysis (fig. 

 996, c) is greatly elongated ; but the vertebrae agree 

 with those of Thaumatosaurus in the firm attach- 

 ment of the arches and cervical ribs to the centra, 

 although the centra themselves have the terminal faces flatter, 

 and with a transversely elliptical and somewhat angulated contour. 

 The radius and ulna are nearly as broad as long, and have only 

 a very small interval between them. The most specialised genus 

 of this branch is Pliosaurus {Ischyrodon, Sfiondylosaurus or Lio- 



Fig. 1003. — Crown 

 of a tooth of Plio- 

 saurus brachy dims ; 

 from the Kimeridge 

 Clay of Ely. One- 

 half natural size. 



