PLEsiosArEiD^:. 249 



Seeley ; another pectoral girdle figured by the same writer in the 

 ' Quart. Journ. Geol. Soc.' vol. xxx. p. 446, as referable to this genus, 

 is noticed under the head of Plesiosaurus (p. 277). The contour of 

 the anterior border of the pectoral girdle is suggestive of affinity 

 with Thaumatosaurus. 



Eretmosaurus rugosus. — Diagram of the pectoral girdle ; from the Lower Lias. 

 Greatly reduced, s, scapula ; c, coracoid ; g, glenoid cavity. (From the 

 ' Quart. Journ. Geol. Soc.') 



This genus is represented in the Upper Lias by Plesiosaurus 

 dubius, Blake \ which is probably identical with P. macropterus, 

 Seeley \ 



Eretmosaurus rugosus (Owen 3 ). 

 Syn. Plesiosaurus rugosus, Owen 4 . 



The type species ; of medium size. Skull unknown, but (judging 

 from the size of the anterior cervical vertebrae) probably small. 

 About 35 cervical vertebrae, in which the centra are of medium 

 length, with ellipsoidal and moderately cupped terminal faces and 

 double costal facets. External surface of vertebrae and limb-bones 

 extremely rugose ; the rugosities at the end of the centra forming a 

 kind of network. Radius and ulna much elongated, and carpals 

 and tarsals very large ; four bones in distal row of carpus and 

 tarsus. 



This species was founded upon vertebrae in the [Museums at 

 Bristol and York, and in the collection of the Earl of Enniskillcu 

 (Viscount Cole). The Upper Liassic specimens probably belong to a 

 distinct species. Although the vertebrae of the undermentioned 

 specimens are more rugose than those of an}- species of Plesiosaurus, 

 it does not appear absolutely certain that they are identical with 

 the types, in which case the species must date from the description 



1 Tate and Blake, he. cit. p. 246. 



2 Ann. Mag. Nat. Hist. scr. 3, vol. xv. p. 50 (1865). 



3 Rep. Brit. Assoc, for 1839, p. 82 (1840).— Plesiosaurus. 



4 Loc. eit. 



