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1891.] On the Relations of Carettochelys, Ramsay. 635 
ment of the elements is the same, the frontals being excluded 
from the orbits. There is no indication in the photograph of free 
nasal bones. The nose is projected much in front, and must have, 
when in fresh condition, an appearance very much like that in 
the Trionychia, but not so much pointed. The zygomatic arch 
is not elevated as in the Trionychia, but is in a line with the 
maxillary and quadrate, as in the Cinosternide, for instance. 
The neck, the vertebrae of which were unfortunately not pre- 
served, was short; but I do not see any reason why the head 
could not have been retracted, as in the Chelydride, for instance 
Nothing is known about the shoulder-girdle and the pelvis. But 
one thing seems to be sure: the pelvis was not codssified with the 
carapace and plastron, but free. If it had been codssified 
with the shell, as in the Pleurodira, it probably would have been 
preserved with the shell. An important question is the number 
of phalanges in the fourth digit; as is well known, in all Trionychia 
we have more than three phalanges in the fourth digit. It looks 
to me, as far as I can conclude from the photographs, that in 
Carettochelys the number. three was not surpassed. 
We have now to consider the carapace and plastron. Both have 
been figured by Ramsay, but there was some. doubt about the 
presence or absence of a mesoplastral element. In regard to the 
carapace, I have nothing newto add. There is no trace of dermal 
scutes on the shell. The number of neurals is six; they are very 
slender and all separate from each other. The first six pleuralia 
- meet in the middle line behind, being separated in front by the 
neuralia. The seventh and eighth neuralia touch each other 
completely in the middle line. There is only one postneural. The 
number of the peripheralia (marginal bones) is ten on each side, 
besides the single pygal. The most interesting new point to be 
noted in the plastron is the presence of a small distinct meso- . 
plastral element. The structure of the plastron is best seen from 
the figure. 
I have stated above that Paddan is the nearest relative of 
Carettochelys. Pseudotrionyx was described by Dollo (6) in 1886. 
` The portions found in the Middle Eocene of Belgium consisted 
of the posterior part of the carapace, and the nearly complete hyo-, 
