n68 



CLASS REPTILIA. 



field Slate (Lower Jurassic) of England to the topmost Cretaceous 

 of Maastricht in Holland ; and has also been recorded from the 

 Upper Cretaceous of Southern India. There is good evidence of 

 the existence of two species in the Wealden. An attempt at a 

 restoration of the skeleton of the type species is shown in the 

 accompanying woodcut. The North American Allosaurus (of which 

 the pelvis is represented in fig. 1064) appears to be a closely 

 allied form of Upper Jurassic age. The nearly entire skeletons 

 of the latter and other American forms have shown that certain 

 very excusable errors were made in the restoration of the 

 imperfect elements of the skeleton of the English genus ; and 

 it is quite evident that the skull of Megalosaurus must have 



had an inferior temporal arcade, 

 and that it approximated more 

 or less closely to that of Cerato- 

 saurus (fig. 1070), although the 

 bony processes of the latter 

 may have been wanting. In the 

 teeth (fig. 1065) the serrations 

 on the anterior border are in 



Fig. 1069. — Restoration of the skeleton of Megalosaurus Bucklandi ; from the Stonesfield 

 Slate. Greatly reduced. 



some cases confined to the upper half of the crown, but in others 

 extended nearly throughout. Typically there are five vertebrae in 

 the sacrum ; the cervical vertebrae are opisthoccelous ; the astragalus 

 has a process ascending on to the tibia ; and there were three digits 

 in the pes and probably four in the manus. In the North American 

 Creosaurus we have an allied Upper Jurassic genus, in which the 

 postcervical vertebrae have very deep depressions on the sides of their 

 centra ; and there are but two sacral vetebrae. In Ceratosmirus, 

 of the Upper Jurassic of North America, the skull (fig. 1070) is 

 remarkable for carrying a single bony protuberance behind the 

 terminal nares, and a pair of similar protuberances directly in ad- 

 vance of the orbits ; while the mandible has a lateral vacuity like 

 that of the Crocodilia. Professor Marsh believes that the pro- 

 tuberances on the skull supported horns. In the type specimen the 

 three pelvic bones and the metatarsals were respectively anchylosed 



