no. 1640. NEW SPECIES OF FOSSIL T( RTLES—HAY. Igp, 



On the middle third of the bono the ridges are much interrupted, 

 sometimes ending suddenly in a bead or a series of them. The pits, 

 therefore, open into one another extensively, and most of them inclose 

 a bead, others four or five of them. 



Toward the free border (fig. 4) the ridges tend to run across the 

 costal and more or less in rows parallel with the free border. 



This species is referred to the genus Aspideretes for the reason 

 that up to the present time no other genus of trionychids is known 

 to have existed during the Cretaceous. All specimens sufficiently 

 complete show tlu» presence of a preneural bone. 



EXPLANATION OF PLATES. 

 Plate XXVI. 

 Terrapene longinsulce X f. 

 Fit;. 1. Carapace. 



In front the first peripheral of the right side is missing: also the free 

 border of the nuchal bone, on the left side, has been gnawed away by 

 a rodent. On the sides and behind, some of the peripherals are wanting. 



2. Plastron. 



The right epiplastron and a small part of the left are missing. 



3. Skull viewed from above. 



Plate XX VI I. 



Hoplochelys calata X 1. 



Fig. 1. Ninth, tenth, and eleventh peripherals of right side, showing tbo upper 

 surface The sculpture is not well shown. 



2. Seventh, eighth, and ninth peripherals of left sid< . showing the lower 



surface. In the left border of the ninth is a notch. In this is seen 

 a fragment of the free rib-end of a costal, occupying a pit in the 

 peripheral. In the seventh are seen pits for processes of the hypp- 

 plastron. 



3. Fragment of a costal bone, showing sculpture. 



Aspideretes granifer X 1. 



4. A nearly complete costal bone. 



5. Part of same costal as fig. 4. 



The lower end of tig. 5 is to be applied to the upper end of fig. 4, so as to 

 make the white line on the one join that on the other. The figures 

 Should be viewed with the light coming from the left. The lighter 

 areas are the bottoms of pits, not convex surfaces. 



