356 Mr. H. Seeley on two new Plesiosaurs from the Lias. 



Professor Owen's account of the scapula. It is deeply cupped 

 for the pectoral vacuity, and measures 4^ inches along the per- 

 pendicular and llexuous exterior side, which is elevated to a 

 ridge as usual, interior to which the inferior side is narrow, 

 oblique, and concave. Its anterior margin is convex, and 

 measures 5^ inches. This anterior limb is much wider than the 

 lateral limb, which contracts in the middle. Both terminate in 

 an articular end, in each measuring 1-| inch ; the distance over 

 articulation to articulation is 3f incli. Where the two limbs meet, 

 they become prolonged into a short spur directed forward and 

 outward. I cannot regard either this spur or the broad fiat limb 

 as representing the clavicle. All analogy would indicate that, if 

 this species had such a bone, it was applied to the exterior flat 

 side of the scapula. Nor can I believe that the scapula had in 

 the animal the wonderful position which it has in Prof. Owen's 

 restoration, fig. 93, ' Palceontology,' where the left scapula appears 

 to me to be applied to the right side of the animal. Certainly in 

 this species the broad limb, which is there free and directed 

 backward, was directed forward and downward towards the other 

 scapula. Similar bones are figured in the scapular region of a 

 Plesiosaur by Mr. Hawkins in pi. 25 of the ' Great Sea-Dragons.' 



This species nearly resembles P. dolichodeirus (Conyb.), and 

 is but little smaller than the example recently figured by Prof. 

 Owen in the Palseontographical monograph. 



The distinctive characters are, (1) that in this species the atlas 

 and axis are short and separate, instead of being long and united ; 

 (2) there are 24 vertebrae between the neck and the tail, instead 

 of 23 ; (3) the humerus is more slender, being longer ; (4) the 

 bones of the forearm are wider ; (5) there are 8 carpal bones in- 

 stead of 7 ; (6) there but 4 bones in the fifth digit, instead of 8. 



The more marked differences of the hind limb may be esti- 

 mated from the figure. Prom P. Etheridgii it is well distin- 

 guished by the more numerous cervical vertebra), the 21 dorsals, 

 and larger size. 



Nor does it approach any other species so near as to need a 

 minute comparison. 



Plesiosaurus cliduchus^. 



Professor Owen founded the Plesiosaurus rufjosus on a charac- 

 ter which is by no means limited to that species; for the Plesiosaur 

 just described shows in the cervical region, only in a less degree, 

 roughnesses round the epiphyses ; and the cervical vertebrae of 

 that which is now to be described have the same character. But 

 Mr. Wm. Davies, of the British Museum, assures me that in 

 the typical specimen of Plesiosaurus rugosus the characteristic 



* KKeis, Lat. juffulum ; and (xa>, Lat. habeo. 



