384 University of Kansas Geological Survey. 



case of the hyoplastron. Near the internal border it articulates 

 strongly by an overlapping joint with the xiphiplastron. 



The lateral process starts a little posterior to the articulation 

 of the hyo- and hypoplastic, thus leaving quite a space between 

 the two processes. It extends outward and slightly backward 

 and terminates in strong digitations, as does the lateral process 

 of the hyoplastron. There is a rugosity on the lower surface 

 similar to that on the hyoplastron, and located in about the 

 same position. 



The xipliiplastron is elongate antero-posteriorly, rounded on 

 the outer border, and broken into deep serrations on the inner. 



There was a fontenelle of considerable size, as shown in 

 the figure. 



The ilium of the right side is all that is preserved of the pel- 

 vis. It is short and rather strong. The proximal portion is 

 slightly expanded, with the usual three faces. The posterior 

 border of the acetabulum is raised and is much thicker here 

 than elsewhere. Anteriorly it is thinner, and there is no pro- 

 nounced rim to the acetabular cavity. Above this end the shaft 

 contracts slightly, and then expands to form the broad and thin 

 distal end. This end is extended forwards so that it lies at 

 almost a right angle to the remainder of the bone. Plate lxxx, 

 figure 9. 



Two small bones, slightly curved, with elongated shaft, and 

 slightly expanded extremities, may belong in the forearm. 

 There are several phalanges of the front foot present, show- 

 ing that it was developed into a long swimming organ, as in 

 ( 'ht Ionia. 



A single caudal vertebra from near the middle of the series is 

 about a centimeter long. It presents well-defined transverse 

 processes. The bod}^ is contracted in its middle part, and shows 

 a slight groove on its lower surface. There is no trace of facets 

 for Chevron. 



The humerus presents an unbroken proximal articular sur- 

 face. In this it differs from the existing sea turtles, where 

 the head is separate from the radial crest. The articular sur- 

 face is semicircular near its middle, is expanded, and extends 



