PLESIOSAURUS. 203 
Camelion, and the paddles of a Whale. Such 
are the strange combinations of form and struc- 
ture in the Plesiosaurus — a genus, the remains 
of which, after interment for thousands of years 
amidst the wreck of millions of extinct inhabi- 
tants of the ancient earth, are at length recalled 
to light by the researches of the Geologist, and 
submitted to our examination, in nearly as per- 
fect a state as the bones of species that are now 
existing upon the earth. 
The Plesiosauri appear to have lived in shal- 
low seas and estuaries, and to have breathed air 
like the Ichthyosauri, and our modern Cetacea. 
We are already acquainted with five or six spe- 
cies, some of which attained a prodigious size 
and length ; but our present observations will 
be chiefly limited to that which is the best 
known, and perhaps the most remarkable of 
them all, viz. the P. Dolichodeirus.* 
* The first specimens of this animal were discovered in the lias 
of Lyme Regis, about the year 1823, and formed the foundation 
of that admirable paper (Geol. Trans. Lond. vol. 5, Pt. 2.) in which 
Mr. Conybeare and M. De la Beche established and named this 
genus. Other examples have since been recognized in the same 
formations in different parts of England, Ireland, France, and 
Germany, and in formations of various ages, from the m.uschel 
kalk upwards to the chalk. The first specimen discovered in a 
state approaching to perfection, was that in the collection of the 
Duke of Buckingham, (figured in the Geol. Trans. Lond. N. S. 
Vol. 1, Pt. 2, PI. 48). Another specimen, nearly entire, in the 
collection of the British Museum, eleven feet in length, is figured 
in our second volume, (PI. 16) ; and at PI. 17, a still more per- 
