594 Mr. De la Beche, &c. on a new Fossil Animal, 
On the same authority it is suggested that the humero-sternal 
part of the Ichthyosaurus and Plesiosaurus, viz. the furcula, 
coracoid processes, &c. bear a greater analogy to the Monitor 
Iguana, and others of the Lacertae than to the Crocodile. The 
present writer however is still inclined, from the comparison of the 
osteology of the head, to approximate the Ichthyosaurus rather to 
the latter than the former. 
Since the completion of the press, I have received from Mr. 
De la Beche the following particulars of a specimen of Ichthyosaurus 
lately discovered at Lyme, which I am anxious to subjoin, as they 
shew the total number of vertebrae and ribs in this animal. 
The specimen (I. communis) lately found, is very interesting ; it 
consists of the head, with all, or nearly all, the vertebrae in place , 
with the exception of two. The total number of vertebrae amounts 
to 104, not including the atlas and axis, which are also in place ; 
diameter of the largest dorsal vertebrae inch. This specimen 
contains 31 ribs on each side, which I take to be the real number of 
ribs that the Ichthyosaurus possessed, as none appear to be wanting; 
length of the largest rib 11^ inches ; the lower jaw 1 foot 6| inches 
long, is in tolerable condition ; the other bones of the head, with 
the exception of the maxillary and intermaxillary bones, are much 
crushed. The chevron bones come in beautifully after the ribs cease. 
The vertebral column increases (as in the Proteosaurus) from the 
atlas and axis to the middle dorsal, and then decreases to the extre- 
mity of the tail. There are traces of the pelvis in this specimen ; 
it must have been very simple, as after a careful examination I coul$ 
not detect any difference in the vertebras about the place where it 
ought to be attached. 
