Polythorax missuriensis, Cope ED, 1876

Cope ED, 1876, Descriptions of some vertebrate remains from the Fort Union beds of Montana, Proceedings of the Academy of Natural Sciences of Philadelphia 28, pp. 248-261 : 258

Polythorax missuriensis , gen. et sp.nov.

Char. Gen. - Plastroii witlh conitracted fixed lobes anld wide bridge; carapace with well-developed marginal bonies; mandibular ramuis narrow; alvetolar face with acute exter-nal margin; the symphysis nieitlherproduced nor recui'ved. Dermal scuta everywlhere dlistinct, those of the l) lastlon 1 the usual onies, with the acldition of the two marginal intergulars, anid two large intelhinmerals. The latter sctuta are separated from the liumerals bv sutures rutnning1oparallel witlh the lhumeral marain of the anter-ior lobe between the gular and pectoral scuta.

In the possessioni of interhumeral scuta, Polythorax differs fromn anv known genus of Testudinata . The general strulcture is mulch like that of Adocus and Baëna , witlh nearer resemiiblance to the latter in its double intergular scuta. It is impossible to ascertain wlhetlherthere are intersternal bones, as the plastron is cobssified throulghout. The pireseiice or absence of intermarginal scuta cannot yet be (leterminied, althlough it is clear, that if existing, thleir position is quiite externalil.

This genus is interesting as coinnectiigz in its stratigrflaphical position allied types of Cretaceous No. 5 ( Adocus ), with those of the Walhsatch and(iBridger Eoceiies ( Baëna ).

Char. Specif. -C arapace with openily dentate posterior bordler. The sturface is irregaularly swollen, especiallv on the median linle near the mnargins of the vertebral scuta. The vertebral scuta are wide, the costals short, anid the marginals nar-row. The anterior lobe of the plastroni is a little slhorter and more conitracted than the posterior; its base is niarrower than the antero-posterior extent of the bridge. Its extremnity is rounded, whlile that ot the posterior lobe is truncate with rouinded angles. Trhe gular and intergular scuta are eaclh wider than long, while the initerliulnerals are muclh longer than wide. The liumerals are narrow, wlile the pectorals ar e wide fromii the anterior position of the pectoro lhumeral suiture. Each anial sutiutimi is longer than wide.

The surface of the plastron is obsoletely but coarsely rugose; the roughness greatest anteriorly, whlere it conisists of short raised lines irregularly disposed.