190 SATTROrTERYGIA. 



R. 609b. The right femur; from Hastings. Associated with the 

 type vertebras. Length 0,170 (6*7 inches), width at distal 

 extremity 0,075 (2*95 inches). Daivson Collection, 



Cimoliosaurus trochanterius (Owen l ). 



Syn. Plesiosaurus trochanterius, Owen 2 . 



Pliosaurus trochanterius, Owen 3 . 

 Including : — 



Plesiosaurus affinis, Owen 4 . 

 Plesiosaurus manseli, Hulke 5 . 



Syn. Murcenosaurus manseli, Sauvage 6 . 

 Plesiosaurus megadirus, Seeley 7 . 



Syn. Plesiosaurus macrodirus, Seeley 8 . 

 Colymbosaurus megadirus, Seeley n . 

 Plesiosaurus brachyspondylus, Phillips 10 {non Owen). 

 Syn. Murcenosaurus brachyspondylus, Sauvage n . 

 Plesiosaurus validus, Phillips 12 . 



Of very large size. Cervical vertebrae probably about 35 in 

 number 13 ; their centra, except in the anterior region, moderately 

 short, with well-cupped terminal faces, and with or without a 

 distinct lateral depression ; and the arches without oblique zygapo- 

 physial ridges. Humerus (fig. 62) relatively long, with the distal 

 expansion chiefly confined to the postaxial border, and (according to 

 Hulke) articulating distally with three bones ; the radius short, and 

 the ulna pentagonal and not greatly expanded transversely. In the 

 humerus and femur the preaxial roughened surface of the distal 

 extremity does not extend nearly as high up as the postaxial one. 

 The relations of the forms described under the above-mentioned 

 names have been discussed by the writer in the ' Geol. Mag.' dec. 3, 

 vol. v. pp. 353-356 (1888). The species was founded upon the 

 undermentioned femur. No. 31787, which cannot apparently be 

 specifically distinguished from the corresponding bone of the type 



1 Eep. Brit. Assoc, for 1839, p. 85 (1840). — Plesiosaurus. 



2 Loc. cit. 3 Ibid, for 1841, p. 64 (1842). 



4 Ibid, for 1839, p. 86 (1840). 



5 Quart. Journ. Geol. Soc. vol. xxvi. p. 612 (1870). 



6 Ann. Sci. Nat., Zool. ser. 6, vol. viii. art. 6, p. 32 (1879). 



7 Index to Aves &c. in Cambridge Museum, p. xx (1869). Description in- 

 sufficient. 



8 Ibid. p. 143. — Errorim. 



9 Quart. Journ. Geol. Soc. vol. xxx. pp. 445, 447 (1874). 



10 Geology of Oxford, p. 368 (1871). 



11 Op. cit. p. 33. 12 Op. cit. p. 370. 



13 Seeley gives the number of cervicals in P. megadirus as 42, but this seems 

 to include " pectorals." 



