sce 
1872. ] 429 [Cope. 
M. 
Length phalange.... rs : 032 
Width, extremity : 032 
ss shaft. . : .018 
Thickness shaft, 26. .<5.. 2 Sheen O11 
These measurements indicate for the fore limb a total length of 4.52 
feet (M. 1.347) if proportioned as in Chelone ; this would give an expanse 
of 11.3feet. If, however, it was constructed on the plan of Sphargis, the 
expanse would be nearly seventeen feet. 
Several instructive cranial bones were preserved. These are the max- 
illary and distal part of the dentary of the left side ; the posterior part of 
the left mandibular ramus ; quadrate bones and adjacent pterygoids and 
squamosal, one side with the columellar plate also; right post-orbital 
bone and part of the left. Also some probably hyoid elements. 
The maxillary bone and dentary present a considerable extent of the 
alveolar margin. This is remarkable in being thin, sharp and elevated, 
without horizontal portion. The former bone is but little incurved to the 
premaxillary suture ; its anterior outline is elevated and vertical, the nos- 
trils entering opposite the probable middle of the orbit. The palatal plate 
of the maxillary has no great antero-posterior extent, so that the inner 
nares are opposite the anterior part of the orbit. The latter presents 
only the anterior and inferior outlines in the specimen. The part of the 
maxillary below it is very narrow, and weaker than either Sphargis or 
Chelone. The cutting edge has a very open sigmoid flexure, suborbital 
part being turned inwards, the anterior part a little outwards. The os- 
seous rim of the orbit projected considerably beyond the plane of the max- 
illary anteriorly. 
The dentary bone is very deep anteriorly, and like the maxillary is a 
thin vertical lamina. The lower anterior angle is truncated by an acute 
concave margin. This is the anterior extremity of the symphysis. This 
suture occupies the inner face of a triangular area which extends but a 
short distance on the lower margin of the -ramus, and then passes up- 
wards and backwards for a short distance on the inner face of the ramus. 
That portion above the symphysis diverges outwards, thus producing a 
deep notch at the symphysis, as though designed to receive a beak-like 
projection of the premaxillaries. The cutting edge has a slight sigmoid 
flexure corresponding with that of the maxillary ; it rises into a projecting 
angle. 
The posterior part of the ramus displays the cotylus, and in front of it 
a deep long fossa behind the articular bone. There is no angle nor coro- 
noid bone, as in all marine turtles. The superior margin of the dentary 
is thicker posteriorly than in front, and its outer wall is produced back- 
ward as a thin lamina, covering the surangular almost to the posterior 
end of the ramus. The angular is, as in recent forms, a narrow wedge- 
shaped piece below the dentary and surangular.. The posterior edge of 
thesurangular projects behind the dentary and exhibits an acute convex 
