198 KANSAS ACADEMY OF SCIENCE. 
The union between the hyo- and hypoplastra is long and stout, the bones here 
being ten or twelve millimeters in thickness and the suture a close one. The 
other margins are thinned, and the denticulations are not long. The suture of 
the elongate and thin xiphiplastra with the hypoplastra is oblique and irregular, 
but firm. Of the other elements of the skeleton not many are preserved. A 
single biconcave cervical vertebra and a concavo-convex centrum, in their 
crushed condition, present no distinguishable differences from the neck vertebre 
of Toxochelys. 
A proximal portion of the scapula and a claw likewise offer no tangible differ- 
ences from the same bones of Joxochelys. 
The humerus preserved unfortunately lacks most of its ulnar process. The 
articulating surface is in the shape of a large oval directed toward the dorsal 
side. The radial process is stout and prominent, directed ventrally, with a deep 
depression on its inner side and rugose markings on its external surface. The 
shaft is considerably constricted below the expanded part and moderately dilated 
distally, and is strongly curved. There is a well-marked ectepicondylar groove 
near the external border distally. The bone is flattened throughout, doubtlessly 
largely of post-mortem origin. 
The distal part of an arm or leg bone, probably the radius, is present. It is 
much flattened and curved; the articular border transverse. 
The relationships of Porthochelys are clearly with Torochelys latiremis, 
which certainly should be included in the same family. Of 7. latiremis almost 
nothing is known concerning the carapace and plastron. I suspect that when 
the carapace of this form is found it may have a fully coossified carapace, as in 
Porthochelys. From Toxochelys serrifer, of which the carapace is pretty well 
known, the differences are obvious in the incomplete ossification, the serration of 
the neurals, the shape of the pygal, etc. This species is the most common of the 
testudinates of the Kansas Cretaceous; and I believe that when the type of the 
genus 7’oxochelys is better known 7. serrifer will be relegated to another genus. 
The generic differences from 7oxrochelys must then, for the present, be based 
upon cranial characters— these, I believe, are amply sufficient—in the structure 
of the mandible, the maxilla and the strong alveolar border, the shape of the 
prefrontals, frontals, jugals, etc. 
From other Cretaceous turtles, certainly the American ones, differences are 
obvious. From Osteopygis, Lytoloma ( Luclastes), Peritresius, Catapleura, 
Plastomenus, the ossification of the carapace, smoothness of the bones, shape 
of the skull, etc., will distinguish. The skull shows considerable resemblance 
in shape to that of Bothremys, but differs materially in the structure of the 
maxille. famil 
In what emma of turtles this genus, as well as Zoxochelys, should be placed 
is yet a matter of uncertainty. Hay and Case are both inclined to locate Toxo- 
chelys with the Cheloniide. In the present genus, the ossification of the cara- 
pace, the more complete ossification of the plastron, the presence of large 
palatine foramina, the anterior location of the internal nares and the structure 
of the humerus are differences from the sea turtles that should not be over- 
looked. It is true that in old individuals of the sea turtles, especially of 
Thalassochelys, the carapace may become ossified throughout. Nevertheless, 
the high degree of ossification of both the carapace and plastron in this form 
indicates a less high degree of specialization to aquatic conditions, and a greater 
resemblance to Chelydra and its allied forms. I believe that when the limbs 
of individuals of this genus, as also of Toxochelys, are better known, they 
will present less of the flipper-like structure than is now believed to be the case. 
