1846.] STUTCIJBURY ON A NEW PLESIOSAURUS. 411 



May 20, 1846. 



The Rev. J.G. Cumniing, M.A., Vice- Principal of King William's 

 College, Isle of Man, and C. H. L. Woodd, Esq., were elected Fel- 

 lows of the Society. 



The following communications were read :— 



1. Description of a New Species of Plesiosauuus, ifi the Mu- 

 seum of the Bristol Institution. By Samuel Stutchbury, Esq., 

 F.G.S. &c. 



Plate XVIII. 



The animal about to be described in the following pages was dis- 

 covered in the grey lias, which is largely quarried throughout So- 

 mersetshire for building-stone and other economic purposes. 



The remains of Enaliosaurians are distributed through the whole 

 Liassic period, and it has been observed in the majority of cases as 

 relates to the two genera Plesiosaurus and Ichthyosaurus, that spe- 

 cimens of the first-named genus are mostly found lying upon their 

 backs, while the Ichthyosauri are generally lying upon their sides; 

 but in a few instances the parts of the skeletons of both have become 

 dislocated and detached from one another, not even retaining in any 

 manner their relative position. 



In the first of these cases I imagine, that after the death of the 

 animal, gases, evolved principally among the abdominal viscera, have 

 been retained by means of the tough dermal covering, aided by the 

 support of the sterno-costal arcs, and the body becoming gradually 

 water-logged, was quietly deposited on the muddy bottom and after- 

 wards silted up*. 



The fact of the Ichthyosauri possessing a more fish-like form, the 

 depth in their supero-inferior diameter being greater than their late- 

 ral width, accounts for their being so constantly found lying upon 

 their sides ; and the occasional dislocated condition to which I have 

 alluded results from their tough integuments having held together 

 until the interior of the body was so much macerated as to disunite 

 the whole skeleton, which would then be similar to a number of 

 loose bones held in a bag or sack. 



But as these animals generally appear to have been quietly de- 

 posited, it would seem that they must have been protected in some 

 manner from the attacks of their own predaceous race, as well as 

 from those of the fishes, of which numerous remains attest the cx- 

 ist(!nce during that ])eriod ; and these saurian remains a|)peur also 

 to have belonged to individuals of all ages. Hence the o})inion has 

 arii^en, as noticed by Dr. Buckland, that these creatures expcrienei d 

 a violent death. 



* Since this paper was read, the author's attention has l)cen directed to a notice 

 in tlie Gcol. Trans., 2tid series, vol. v. p. 51 li, by I'rofessor Owen, and lie finds 

 tliut he lias used argimionts very similar, respecting conse(|iicnces after death, to 



Uiosi" iis(m1 hv that iiiithor. 



