hay. I Two New Species of Fossil Turtles from Oregon. 239 



The bone thickens until it reaches a thickness of 7 nun. where 

 the suture just named meets the entoplastron . At the inner 

 posterior angle the bone is only 3 mm. thick. 



In lot No. 2179 there is a portion of a left hyoplastron which 

 lacks the free border, but which in the portions represented is 

 identical with the specimen above described. I regard it, there- 

 fore, as belonging to the same species and to the same formation. 

 In this lot are included also a portion of the right epiplastron 

 (Fig. 2), the first right peripheral bone (Fig. 3), a right peri- 

 pheral, apparently the eighth or ninth, and some other fragments. 

 The epiplastron has the border which joined its fellow of the 

 other side missing, so that it is impossible to determine accurately 

 the width of the anterior lip of the plastron. However, this bone 

 has been used in making the restoration of the front of the plas- 

 tron, as seen in figure 1. Figure 2 shows this bone as seen from 

 below. It resembles closely the same bone in 0. guttata, except 

 that its upper side was not so deeply excavated as in the latter 

 species. According to the restoration the lip had a breadth of 

 about 34 mm. 



Figure 2. Figure 3. 



The free borders of the epiplastron are subacute. Seen from 

 the side, this border runs forward to the gulo-humeral sulcus 

 and then turns rather abruptly downward, forward and inward. 

 From the acute edge the bone thickens rapidly, until a thickness 

 of 7 mm. is attained. The gulo-humeral sulcus has probably 

 continued backward on .the entoplastron. 



A piece of the thickened border of the xiphiplastron of this 

 specimen is present. It extends from the junction with the 

 hyoplastron to just behind the femoro-anal sulcus. Most of the 

 free edge is broken away, but enough remains to show that it 

 was acute. It thickens gradually until, at the inner border of 



