[66 



FOSSIL TURTLES OF NORTH AMERICA. 



hind legs was much broader than it is in the case of Chelydra; and, as in the sea-turtles, there 

 was a fontanel between the outer end of the hyoplastron and hypoplastron. There was also 

 an extensive umbilical fontanel. The bones of the right and left sides were joined along the 

 midline more like those of Chelydra than like those of the Cheloniidae. The epiplastron and 

 entoplastron are figured by Wieland (Amer. Jour. Sci., xx, p. 336, figs. 7, 8). The former are 

 slender, the latter broad and lance-shaped. The xiphiplastron, as represented by that of 

 T. stenopora (Case, op. cit., plate Ixxx., fig. 5), is slender and apposes digitations to its fellow. 

 Cervical vertebrae have been figured by Dr. Case fop. cit., plate lxxxiii, figs. 2-4). These 

 were more or less injured, being comprest laterally. A more complete series is in the Marsh 

 collection at Yale, and these have been described by Dr. Wieland (Amer. Jour. Sci., xiv, 1902, 

 p. 102). According to this author, the anterior 5 have their articular ends fashioned as in 

 Chelydra and the great majority of turtles; that is, the first is composed of 4 bones; the 

 centra of the second and third are convex in front and concave behind; that of the fourth is 

 convex at both ends, as in turtles generally. The next four centra are concave at the anterior 

 ends, convex at the posterior. Toxochelys differs from modern Cheloniidae in not having the 

 double concavities developt on the anterior end of the last cervical. The specimen furnishing 

 these cervicals was not accompanied by the carapace, so that we can not estimate the length of 



^0/7 



Fig. 200. Toxochelys latiremts. Front limb. X.28. Specimen in Yale Univ. coll. 



a, head of humerus; b, radial process; c, ulnar process; cen, centrale; e, ectepicondylar groove; g, entocondyle; 

 hum, humerus; int, intermedium; p, pisiforme; rad, radius; ul, ulna; uhi, ulnare; I, II, etc., metacar- 

 pals; I, 2, 3, etc., distal carpal hones. Figure by Wieland. 



the neck relatively to the shell. The estimated length of the neck is 226 mm. The skull was 

 1 14 mm. to the occipital condyle. 



Regarding the caudal vertebrae little that is certain is known. It is not at all improbable 

 that the vertebrae which were described by Cope under the name Cynocercus incisus belong to 

 Toxochelys. Two caudals are in a small collection of bones received from the University of 

 Chicago, with the catalog number 230 and belonging to Toxochelys latiremts. The centrum 

 of one is 18 mm. long. These vertebrae probably belonged toward the end of the tail. They 

 are procoelous and possess short lateral processes. In general these vertebrae resemble those 

 of Cynocercus, but the cup is deeper and without sign of the perpendicular incision seen in 

 Cynocercus, and the ball is more prominent. 



The coraco-scapular arch is more like that of the sea-turtles than like that of the snappers. 

 The coracoid is long, narrow, and spatulate. A considerable neck is interposed between the 

 glenoid fossa and the base of the proscapular process. 



I he tore limb is best known from a specimen in the collection at Yale (fig. 200), which 

 has been described by Dr. Wieland (Amer. Jour. Sci., xiv, 1902, p. 95, fig. 1). The humerus 

 has also been figured by Dr. Case. Dr. Leidy also has figured the proximal end of the humerus 

 of what is no doubt a member of this genus (Cont. Ext. Vert. Fauna West. Terrs., 1873, plate 

 xxxvi, fig. 17). For a figure of the humerus of T. latiremts see fig. 200, shown above. This 

 specimen was accompanied by the lower jaw, and its identification thus made certain. 



The humerus of Toxochelys is regarded by Dr. Wieland as representing the form which 

 he has called "thalassoid, " especially because he believes that the radial process has descended 

 lower on the shaft than it is in Chelydra and that the ulnar and radial processes have moved 



