No. 384.] CHELONIAN CARAPACE AND PLASTRON. 945 
vanished long ago. Lwvoff, however, states! that he has found 
minute ossifications in the teeth of the crest of Sphenodon. 
This row of tubercles is continued forward to the head, with 
one or two interruptions, by a series of thin horny plates. 
On each side of the tail are evidences of two other keels. 
Of these, the upper appears to occupy the position of the costal 
keel of the turtles ; the other the position of the marginal keels. 
On the trunk I find no satisfactory evidences of the existence 
of lateral keels, although there are some scattered enlarged 
scales. On the rump I find a rather interesting thing, although 
it may have no significance. On each side is a row of pointed 
scales, about six in number, which begins near the upper end 
of the ilium and runs backward and toward the median crest. 
These two rows of scales rogper the hinder borders of the 
carapace of Dermochelys. 
A dissection of the tail of Sit. proves that there is 
just one horny tubercle on its dorsum for each neural spine. 
Between the bases of adjacent tubercles folds begin and run 
downward on each side across the tail; on the under side of the 
tail there are, between the successive folds mentioned, two 
transverse rows of enlarged scales. On the sides of the tail 
` the epidermal scales are much smaller and more numerous. 
On the belly the epidermal scales resemble those found on the 
under side of the tail. On the side of the trunk they are again 
very small. A careful reflection of the skin of the belly brings 
to light the “ abdominal ribs,” or gastralia, as they have been 
called by Baur. Immediately behind the sternum the skin 
is loosely attached to them; but along most of the belly it is 
closely adherent. There are about twenty-five of these gastra- 
lia.? Each may be said to resemble a very open capital V, with 
the apex directed forward. Each consists of three closely 
united bones ; one forming the apex of the V and a portion of 
its sides, the other two forming the extremities of the sides of 
the V. Now, there is a cross row of epidermal scales for each 
of these gastralia, and two of the latter for each pair of ribs. 
In fact, the lower ends of the ribs are attached to alternate 
1 Lvoff, W. Bull. Soc. Imp. Natur. Moscou, vol. 1x, pt. ii, p. 333. 
2 Günther, A., doc. cit. 
