110 BOTHREMYS. 



cially interesting from the fact that it presents on its upper surface an oblong 

 elliptical suture for the pelvis. Such an articulation would, perhaps, indicate a 

 nearer affinity of this extinct Turtle to the existing Sternotherus, than to Platcmys, 

 with Avhich I have associated it. 



I have also seen small fragments of two other xiphisternals, with the pelvic 

 sutures, together with a fragment of a costal plate, apparently of a much younger 

 individual, of the same species as the foregoing, obtained by Dr. AVm. B. Atkinson, 

 from the Green-sand of Mullica Hill, Gloucester County, New Jersey. 



BOTHREMYS. 



Bothreinys Cookii. 



In June, 1862, Frof. Cook sent to mo, for examination, the skull of a Turtle, 

 from the Green-sand near Barnsboro, Gloucester County, New Jersey, which, inde- 

 pendent of its special or generic peculiarities, is of interest from the circumstance 

 that it is the first Chelonian skull brought to my notice from the Green-sand forma- 

 tions of the United States. 



The specimen, represented in Figs. 4-8, Plate XVIIl, consists of the greater 

 portion of a skull together with the lower jaAV. Of the former the occipital region, 

 the auditory passages, the zygomatic arches, and some other minor parts are lost ; 

 of the latter the condyloid portions are destroyed. 



Of all recent Turtles with which I am acquainted the fossil skull, in general 

 physiognomy and structure, resembles most that of the great Turtle of the Amazon, 

 Podoc-nemys expansa. From this, and all others, however, it differs in several 

 striking peculiarities. 



The fossil skull is remarkable for the great proportionate breadth of the face, 

 due to the accommodation of a large conical pit formed by each maxillary bone, as 

 seen in Fig. 7-, a. 



The top of the skull (Figs. 4, 6) is nearly fiat, inclining forward in a slight 

 degree, and becoming slightly more convex approaching the orbits and the interval 

 between them. The face in the latter position is broad, slightly convex, and slopes 

 regularly to the anterior nasal orifice. Below and behind the orbits the face is of 

 great proportionate depth, and slopes obliquely downward and outward with a 

 moderate degree of convexity. Transversely the lower boimdary of the face forms 

 a semicircle, broken only by a moderate pointed protrusion of the premaxillaries. 



The orbits arc comparatively small and circular, and look obliquely upward, 

 forward, and outward. 



The anterior nasal orifice is of great proportionate breadth, its transverse diameter 

 being twice as great a^ the vertical. It is in the form of a double annulus or a 

 prostrate figure of 8. 



The temporal fossae are large, but Avhether they have been covered by a bony 

 vault, as in the great Turtle of the Amazon and the marine Turtles, cannot be 

 ascertained in consequence of the imperfection of the fossil. 



The upper jaw is defined below, in the usual manner in Turtles, by an acute ridge 

 for accommodathig the corneous dental armature of the jaw. 



