190 G. R. Wieland — Upper Cretaceous Turtles. 



In addition to the fragmentary portions present, the general 

 form of the plastron is in part indicated by the marginals. 

 The digitations of the antero-external limb of the hyoplastron 

 projected into several small shallow pits in the lower border of 

 the posterior half of the fourth and the anterior half to three- 

 fourths of the fifth marginals, thus forming a dactylate junction 



Figure 4. — Propleura borealis Wieland (type), x §-. Vertical, middle, or 

 end transverse sections of marginals for comparison with the marginals of 

 Lytoloma shown in figure 3. 



1, 3, 5, 6, 7, middle sections numbered respectively; 2a, 2p, anterior and 

 posterior end outline (or section) of second marginal ; s, s, inner border of 

 first and second marginal (uniting by suture to first pleural and not free as in 

 Lytoloma) ; /, free border ; r2, claw-shaped furrow in third marginal for 

 reception of second rib ; r, r, r, rib pits in 5-7 marginals for reception of 

 respective, i. e. 3-5 ribs. 



6*5 to 8 cm in length. This is a distinctly shorter junction than 

 in Osteopygis, in which the outer hyoplastral limb extends 

 forward to the second marginal, and is about equal in extent to 

 that seen in Eretmoohelys. ~No distinct pits for the reception 

 of the outer digitations of the hypoplastron exist in the fossil at 

 hand. In the Osteopyges, these are present for both limbs of 



