568 Analytical Notices of Books. 



constitute a fictitious animal ; but the question is now completely 

 set at rest by the discovery of an almost perfect skeleton, con- 

 firming, in nearly every essential particular, the opinions formerly 

 advanced by him on this subject. Through the numerous and ex- 

 tensive details into which this magnificent specimen enables him to 

 enter, it would be impossible and even needless for us to follow 

 him, since those who are interested in the inquiry will doubt- 

 less consult the original paper ; but one most singular feature 

 of the organization of the animal in question cannot be passed over 

 in silence. Previously to the recent discoveries of fossils of this 

 class, the number of the cervical vertebra? had been regarded as 

 small in all quadrupedal animals ; those of the Mammalia, with 

 the single exception of the Tridactyl Sloths, being exactly seven, 

 Reptiles possessing from three to eight, and Birds alone varying 

 from nine to twenty-three. The Ichthyosaurus however, which 

 possesses eighteen, first evinced a deviation from these general 

 rules, which appears to have reached its maximum in the Plesio- 

 saurus, where the number of the true cervical vertebrae is thirty- 

 five, or, including the anterior dorsal which are placed before the 

 humerus, forty-one. This extraordinary elongation of neck, as- 

 similates the Plesiosaurus less to Fishes, in which the sternum, as 

 admirably illustrated by Geoffroy de St.Hilaire, is thrown forwards, 

 though destined to move in the same element with them, than to 

 birds, in which this portion of the skeleton is thrown backwards ; 

 and will strongly excite the attention of the philosophic Naturalist. 

 The reverend authour conjectures that the animal may have swam 

 upon the sea, to which element the form of its paddles assigns it, 

 with its long neck arched backwards, like that of the swan, ready 

 to dart down at the fish which came within its reach ; or that it 

 might have lurked in shoal water, hidden from the attacks of its 

 enemies, and deriving from the flexibility of its neck a compensa- 

 tion for that want of agility in moving through the water which is 

 to be inferred from its organization. The head of this species, 

 (which the authour denominates Plesiosaurus Dolichodeirus, from 

 its most distinguishing characteristic, the length of its neck), is less 

 than one-thirteenth of that of the body, while in the Ichthyosaurus 

 its proportion is one-fourth. 



