mid Structure of the Proteus Anguinus . SI 
say the authors, to give minute demonstrations of these ; their 
figure, size, and position, are delineated of their natural size in 
Plate VI. Fig. 2, in which also the bones previously described 
are exhibited. 
The authors having previously remarked that the bones of 
the proteus are less rigid than those of the aquatic salamander, 
proceed next to point out a few differences of form in the skele- 
tons of these two animals. At first they appear very similar, 
but many points of dissimilarity occur on closer inspection. 
Thus, the transverse processes of the vertebrae in the two ani- 
mals differ in relative size and form, as do also the costulae or 
riblets that spring from them. In the salamander, the cartilages 
of the shoulder are large enough to extend over the breast, and 
perform the office of a sternum : in the proteus, on the con- 
trary, they do not touch. Again, the pelvis, in the proteus, is 
attached by one extremity to the transverse processes of the 
thirty-first vertebra, and with the other end contributes, with 
the os pubis, to form the cotyloid cavity : in the salamander, 
the ileum is not immediately attached to the spine, but only by 
the intermedium of a little bone : and hence, in these reptiles, 
the whole pelvis is moveable. In the salamander again, there 
are only two vertebrae which form the sacrum ; in the proteus 
there are three. Other differences might be noted in the bones 
of the tail and paws ; but not to go into farther details of this 
sort, the authors prefer giving the results of their observations 
on the respective locomotive powers of these animals. 
2. Of the Movements of the Proteus in Water and on Land , 
compared with those of other Animals. 
Whoever shall attend to the particular structure of the ver- 
tebras in the proteus, and their reciprocal connection, will easily 
perceive that the lateral movements of the head towards the 
trunk, and the lateral bendings of the trunk itself, will be some- 
what limited in its superior part, where the articular apophyses 
form two planes inclined and converging in one and the same 
line : but as these processes gradually diminish in size, the ca- 
pacity of moving laterally will be greater as we descend, and 
greatest of all when it reaches towards the eighth caudal verte- 
bra, since there the processes entirely disappear. In the sala- 
