and Clavicular Arch in Sauropterygia. 



135 



The germs Cimoliosaurus figured by the late Dr. Leidy in 1865 

 (' Smithsonian Contributions to Knowledge ') rests upon thirteen 

 centrums of vertebrae without arches or processes, noticeable chiefly 

 for their transverse width. Fourteen other vertebrae from the 

 Greensand of New Jersey are described ; but there is no evidence of 

 any other part of the skeleton. Leidy expressed doubt whether his 

 genus Discosaurus might not prove to be founded on vertebrae of 

 Cimoliosaurus. This view was adopted by Professor Cope (' Amer. 

 Phil. Soc. Trans.,' vol. 14), but that identification only contributed a 

 knowledge of the carpal and metacarpal bones. Hence the characters 

 by which the genus is defined in the ' British Museum Catalogue ' 

 are not drawn from Leidy's type. 



The generic characters of Cimoliosaurus which may be obtained 

 from Leidy's figures are : Articular face of the centrum flat or 

 flattened, short from front to back, transversely extended in the 

 cervical region. The neural arch is small, with compressed lamellar 

 neurapophyses, which appear to be anchylosed to the centrum. The 

 facet for the cervical rib is single, at first compressed from above down- 

 ward, afterwards "becoming ovate ; the facets are on short pedicles. 

 The chevron articulations impress both the anterior and posterior 

 margins of the short centrums in the middle of the caudal series. The 

 carpals are transversely oblong. The metacarpals and phalanges are 

 compressed from above downward. 



The name Brimosaurus (Leidy, 'Philadelphia Acad. Nat. Sci. 

 Proc.,' 1854, PI. 2, p. 72), was proposed for Plesiosaurian vertebrae 

 which have the ventral surface flat instead of concave, as in Cimolio- 

 saurus ; but, as the genus is not mentioned in that author's 

 1 Cretaceous Reptiles of the United States,' 1865, it may be regarded 

 as probably abandoned and included in Cimoliosaurus. 



Dr. Leidy also proposed a genus Oligosimus (' Philad. Acad. Nat. 

 Sci. Proc.,' 1872, p. 39). It is unfigured and based upon an early 

 caudal vertebra. It has the neural arch anchylosed to the centrum. 

 A groove defines tbe limit of the articular face of the centrum. The 

 chevron facets only impress the posterior border of the centrum. Its 

 measurements are: length, 1 inch; width, 2*3 inches; depth, 1*9 

 inch. These characters seem insufficient at present to distinguish 

 the type as a genus. 



Professor E. D. Cope has decribed five other genera which he 

 regards as distinct from Cimoliosaurus ; they are named Elasmosaurus, 

 Polycotylus, Orophosaurus, TJronautes, and Pijptomerus. 



Polycotylus from Cretaceous Limestone, near Fort Wallace, Kansas 

 (' Amer. Phil. Soc. Trans.,' vol. 14, Part 1, p. 35, PI. 1, 1870), is 

 founded upon dorsal and caudal vertebrae. It is characterised by the 

 very short dorsal vertebral centra, which are deeply biconcave. The 

 tibia is broader than long. The neural arch is anchylosed to the 



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