LOPHIOTHERIUM PYGMJITJM. Cope. 



Represented by a portion of the right mandibular ramus with the 

 penultimate and ante-penultimate molars in perfect preservation. These 

 teeth present four cusps, of which the inner are crescentoid in section, 

 the outer conic. They are all elevated, and the outer anterior is in both 

 teeth compressed and bifid ; it receives an oblique ridge from the inner 

 posterior. Enamel smooth. 



Lines. 



Length penultimate molar 2 



Width 1.5 



Depth of ramus at do 3 



This is much the smallest of the genus, being about equal to the 

 Hyopsodus paulus L. The penultimate molar in the nearest species, 

 L. ballardii, Marsh, measures 3.2 lines in length. 



Anostira trionychoides. Cope. 

 This species is about the size of our existing Ghrysemys fricta. It dif- 

 fers from the A. omata, Leidy, in various respects. Thus the sculpture 

 of the costal bones is pit-like, as in many species of Trionyx, instead of 

 striate-ridged. There is no keel on the pygal bone behind. The first 

 marginal bone is longer, and does not exhibit the prominent shoulder 

 seen in A. omata. The marginal bones are not unlike those of that 

 species, having central small tubercles, and radiating ridges. The species 

 is not uncommon in the Bridger beds on Cottonwood Creek, Wyoming. 

 Anostira cedemia. Cope. 

 This species is nearly twice the size of the last. It is distinguished by 

 its peculiar ornamentation. This consists of bosses or swollen portions 

 of an oval shape, which stand transversely to the long axis of the body, 

 from a quarter to a half an inch apart. They sometimes form short 

 ridges, surface otherwise smooth. Locality same as the last species. 

 Anostira molopina. Cope. 

 This species is intermediate in size between the two last described. 

 It is distinguished from both by its ornamentation. This consists of a 

 delicate and rather scattered impressed punctuation on the costal bones. 

 Across this extend oblique ribs extending in a diagonal direction out- 

 ward near the extremities of the costals. The width of one of the cos- 

 tals is M. .023. The costals in this species display no suture for the mar- 

 ginals, and the extremity of the rib projects a very little. 

 Trionyx concentkicus. Cope. 

 This species is not uncommon in the Bridger sandstone. It is well 

 characterized by its sculpture, which is coarsely and distinctly pitted. 

 Across the costal bones run parallel ribs, which enclose between them 

 from three to one row of pits. 



M. 



Width of a costal bone near the middle 02 



Thickness " " " 003 



