conjecture), a very considerable approximation to the true structure of the part will be found, considering the very imperfect materials afforded by the fragments which had then been obtained.
But in addition to these particulars, which in all their material features were correctly stated, the specimen now exhibited presents others of a most novel and interesting character, not to have been anticipated previously to the discovery of a skeleton the whole exterior portion of whose vertebral column was perfect. I particularly allude to the neck, which is fully equal in length to the body and tail united; and which surpassing in the number of its vertebra (hat of the longest-necked birds, even the swan, deviates from the laws which were heretofore regarded as universal in quadrupedal animals, and the cetacea. I mention this circumstance thus early, as forming; the most prominent and interesting feature of the recent discovery, and that which in effect renders this animal one of the most curious and important additions which geology has yet made to comparative anatomy.
I now proceed to the details in the usual order
Head.-The present specimen, and another of this part only, in possession of Miss Philpot, confirm the restoration attempted from the distorted head figured in Plate XIX. of the first volume of the second series of the Geological Transactions; and the latter extends our knowledge by exhibiting distinctly the occipital portion. We now also learn for the first time, that the head of this animal was remarkably small, forming less than the thirteenth part of the total length of the skeleton ; while in the Ichthyosaurus its proportion is one-fourth. This proportional smallness of the head, and therefore of the teeth, must have rendered it a very unequal combatant against the latter animal; but the structure of its neck may perhaps be considered as a compensating provision, supplying it with the means of security and of catching its prey.
Vertebræ.-The distinctions between the cervical and caudal vertebra; have been fully and correctly stated in my former communications; but I had not at that time observed more than twelve of the cervical, whereas the present specimen exhibits about, thirty-five, or, including the anterior dorsal, which were placed before the humerus and bore only five ribs, forty-one*. This great increase of the number of joints in the neck, is the more remarkable from the rigour with which nature appears, in most cases, to have enforced the law of a very limited number. In all quadrupedal animals, in all the