122 G. E. Wieland— Upper Cretaceous Turtles. 



twelfth or supracaudal pair, none of which overlap the ends 

 of the pleuralia ; the 4th-10th rising jnst to, or a little above 

 the bottom of the marginal notch above noted as exposing the 

 rib-tips : costals 4 pairs, large : vertebralia 5, the lst-Bd and 

 5th of normal pattern, the 4th of ornate outline like the verti- 

 cal section of a wide-mouthed and small-bottomed jug. 



(B) The Plastron. — Of much reduced size, the length being 

 about |, and the least width of the bridge less than \ that of 

 the carapace. Composed of 9 bony plates, with the furrows 

 marking the horn shields rather indistinct, but evidently as 

 shown in text figure 4. 



**.• 



Figure 5. — Osteopygis Gibbi type. Entoplastron. Outer view, natural size. 



(1) Bony Plates. — The general outline of the bony plates com- 

 bines features of Chelydra and of the Dermatemydidas. The 

 narrow epiplastra meet at a rounded obtuse angle as in Stauro- 

 typus. The entoplastron, as shown in the accompanying text 

 figure 5, exhibits a condition which is intermediate between 

 that seen in a turtle like Adocus, and the reduced and rod-like 

 condition in Chelydra. Union of the remaining elements on 



