OF THE CRETACEOUS OF NEW JERSEY. 563 
sand a type of turtles is found, embracing several genera and spe- 
cies, in which the sternum has the elements generally united by 
sutures, except two central fontanelles, being thus intermediate 
between that of the Cheloniide and that of the Chelydras (snap- 
pers) ; that the femur and humerus are curved, as in the snappers, 
but the limbs are oar-like bodies with truncate phalanges, as in 
the sea-turtles. This family he called the Propleuride. 
The second case was presented by tortoises of a character like 
those now inhabiting fresh waters. The Emydide, or common 
river tortoises of the northern hemisphere, were shown to possess 
ten horny shields on the plastron (or lower shell), had a pelvis 
freely suspended from the carapace (upper shell), and a series of 
cervical vertebrae which can be curved in an S, and the head there- 
by drawn into the shell in a vertical plane. The southern hemi- 
sphere division of the Pleurodira, possesses eleven scuta of the 
plastron, a pelvis, of which the pubis and ischium unite by 
sutures with two corresponding elevations of the plastron, and a 
neck which can not be sigmoidally flexed, but is thrown round 
to one side, like that of a bird, when it is necessary to conceal the 
head. ‘ 
It was shown that in the Cretaceous of New Jersey there existed 
a family (the Adocide) which combined the features of these 
groups. It had eleven scuta of the plastron (the extra one being 
large and anterior), but the lower bones of the pelvis were not 
codssified with the plastron, though the latter rose in two corres- 
ponding elevations. The latter were evidently rudiments of the 
articulating knobs of the Pleurodira. 
Professor Cope stated, moreover, that the Adocide possessed a 
row of scuta across “the bridge,” within the marginal row, such 
as existed in modern times in the sea-turtle, and in the Mississippi 
snapper, thus adding very much to the generalized character of 
the Adocide. 
Turning to the tortoises of the Eocene beds of Fort Bridger, 
Wyoming, he showed that these were true Emydide, but that 
many of them retained the inter-marginal series of scutes, above- 
mentioned (Baptemys, etc.), so far resembling the Adocide. 
Among existing typical Emydide, but one genus presents the 
character, viz., the Dermatemys of Mexico. 
The value of these generalized groups was pointed out as con- 
sisting in their correction of our views derived from the great 
AMER. NATURALIST, VOL. V. 36 
