174 FOSSIL TURTLES OF NORTH AMERICA. 



has joined the hindermost suprapygal. Above and below, the pygal is broadly grooved from 

 front to back. The most anterior peripheral is thin and narrow. The second is only slightly 

 wider. The third has its inner face more developt and possesses a pit which received the 

 extremity of the rib of the first costal plate. The inner, or costal, face of the succeeding periph- 

 erals increases in breadth, until a section of the bone is a nearly equilateral triangle; then 

 the face is reduced, so that at about the eighth the bone has grown quite thin and flat and 

 relatively broad. Each peripheral, except the first and the second, has a pit for the reception 

 of a rib-end, until we come to the tenth. 



Ordinarily in turtles the eighth costal plate sends its rib to the tenth peripheral, but in 

 Toxochelys the eighth costal plate is short and its rib does not extend beyond the border of the 

 plate. As in Chelydra and most other turtles, there is no rib-end reaching the eleventh periph- 

 eral. In the Cheloniidae the rib of the eighth costal plate is turned backward to this periph- 

 eral, one of the more anterior peripherals not receiving a rib. However, Wieland represents 

 the rib of the eighth costal plate as entering a pit in the eleventh peripheral. See fig. 235 of 

 the present work. 



No. 1270 of the Kansas University museum furnishes a number of costal plates, a few 

 neurals and the anterior suprapygal bone. These are represented in Case's figure already 

 referred to. According to the present writer's views, another peripheral ought to be inserted 

 between the last one of that figure and the pygal; and there was almost certainly at least one 

 suprapygal behind the one there represented. The neural which Dr. Case has called the ninth 

 is certainly the eighth, since it has articulated with it the eighth costal. Resting partly on this 

 neural and the first suprapygal is a comprest tubercle at the base of which is a distinct suture. 

 The neural seen in front of the one just referred to is probably in its correct position; but the 

 next one in front is certainly wrongly placed, being probably the fifth. The facet on the anterior 

 end of the upper surface of the sixth has undoubtedly supported a tubercle similar to the one 

 resting on the eighth neural. 



The midline of the carapace of T. stenopora was traverst by a sharp and tuberculated 

 keel, such as has been described as occurring in the specifically undetermined species (p. 164). 

 As in that form, the more anterior tubercles were connected with their underlying bones by 

 open sutures. The elevation of the shell was probably about the same that we find in Chelydra. 



In the figure presented by Dr. Case, the costal plates are probably correctly placed with 

 reference to one another. As will be seen, there were large fontanels between the distal ends 

 of the ribs. 



The plastron is represented by fig. 22O, reproduced from Dr. Case's work so often quoted. 

 Nothing is known regarding the entoplastron and epiplastron. There was a large umbilical 

 fontanel, while there was, on each side, another fontanel bounded by the peripherals outwardly 

 and by the hyoplastron and hypoplastron in front and behind. The lateral digitations of the 

 plastral bones did not enter into pits in the peripherals. The median digitations probably 

 approacht closely those of the opposite side. A prominent longitudinal ridge on each side 

 crost the hyoplastron and hypoplastron. 



Toxochelys elkader sp. nov. 

 Figs. 211-223. 



Of the type of this species, No. 6137 of the American Museum of Natural History, there 

 were secured the skull nearly complete; large portions, perhaps the whole, of the plastron; 

 the shoulder-girdles; portions of the pelvis; and apparently one or two peripherals. Excepting 

 the skull, the parts have not yet been prepared for study. The specimen was found in the 

 Niobrara beds, near Elkader, Logan County, Kansas, by Mr. H. T. Martin, of the University 

 of Kansas. 



The skull, like most specimens found in the Niobrara beds, is somewhat crusht. The 

 length from the snout to the occipital condyle is 105 mm.; to the end of the supraoccipital 

 spine, 143 mm. From the outside of one quadrate to that of the other is 101 mm. The outline 

 of the skull, from a little in front of the quadrate, is nearly straight to the rather pointed snout. 



Both squamosals (fig. 221) are missing, but it is probable that each sent upward a process 

 to the parietal. The latter bones are complete. The jugal extended nearly to the pedicel of the 



