188 G. JR. Wieland — Upper Cretaceous Turtles. 



The recovered portions of the present specimen, shown in 

 detail by the stippled areas in Plate VIII, consist of (a) the third, 

 fifth and sixth nenrals ; (b) the antero- and postero-pygal ; (c) 

 the plenralia of the right side less the free-rib tips, but with 

 the inner or neural borders of all but the second distinct ; (d) 

 the first to the fifth pleurals inclusive of the left side, the free- 

 rib tips of the second and fifth being present, also a fragment 

 of the seventh pleural, as indicated by its form and the postero- 

 lateral furrow of the fourth vertebral horn-shield which crosses 

 it ; (e) the fourth to the seventh inclusive, and the ninth mar- 

 ginals of the right side, and the fourth to the eleventh mar- 

 ginals inclusive of the left side, with the anterior half of the 

 pygal marginal. There are also some fragments of the accom- 

 panying plastron, which, although too incomplete to permit 

 the exact restoration of any of the plastral elements, indicate a 

 plastral form even more reduced than, but otherwise much like 

 that seen in Osteopygis and Propleura. 



With the exceptions mentioned, all parts of the carapace, as 

 far as recovered, are uncrushed and but little broken. As sent 

 to the museum, they were dissociated, but the sutures are well 

 preserved and almost without exception interlock in their 

 normal position, so that it is possible to determine these 

 elements, as well as the general form of the carapace. The 

 fortunate presence of the third neural, with both the adjoin- 

 ing third pleurals as well as two rib tips of the left side, leaves 

 no doubt as to the width of the carapace. Moreover, the 

 borders of the missing second, fourth, seventh, eighth, and 

 ninth neurals are indicated exactly, and those of the first 

 neural approximately. The anterior sutural border of the first 

 left pleural being complete, there can be little doubt but that 

 the nuchal had approximately the outline indicated in Plates 

 VI-VIII. The length of the missing three anterior marginals 

 can only be inferred, but must be nearly that shown in outline. 



With regard to the general form of the marginals and of the 

 posterior neurals in the present genus, and in Osteopygis and 

 Propleura, figures 3-6 in the text afford data for exact com- 

 parison. Taken in conjunction with the facts already given, 

 they require little further description. It may only be noted 

 that the specimen represented in figure 5 shows a diminution 

 of the posterior neurals more marked than that in Osteopygis 

 Gibbi, while the condition in Propleura, figure 6, is more like 

 that of the present form. 



As indicated in Plates VI and VII, the horn-shield furrows 

 are all distinct and rather broad. The carapace is of sub- 

 orbicular outline, being broadest across the posterior end of 

 the fifth neural. In this respect it is somewhat intermediate 

 between cordate forms like those of the existing Cheloninse 



