156 FOSSIL TURTLES OF NORTH AMERICA. 



52 mm., and for the flatness of the triturating surfaces. An unimportant part of the tip of the 

 jaw is broken off. There was certainly no upturned beak, such as there must have been in 

 Rhetechelys platyops (Cope); nor was there a cutting-edge that rose much above the triturating 

 surface. The lower surface of the jaw is likewise very flat, rising abruptly toward the free 

 borders. The thickness at the hinder end of the symphysis is 1 8 mm.; at a distance of 25 mm. 

 behind the tip the thickness is 16 mm. The coronoid process rises 40 mm. above the bottom 

 of the ramus. The rami are thoroly co-ossified. There are no other bones of the jaw 

 present except the right coronoid, which is crowded to the inside of the coronoid process of the 

 dentary. 



At the tip of the jaw the borders of the dentaries diverge at an angle slightly greater than a 

 right angle. At the fronts of the fossae for the masseter muscles the width is 91 mm.; at the 

 hinder end of the dentaries it is 1 10 mm. The fossa; just mentioned are large and deep. That 

 part of each on the dentary is 40 mm. long and 26 mm. high. At the front of each fossa is 

 a mental foramen. A line passing from one of these to the other falls 12 mm. in front of the 

 hinder end of the symphysis. 



The fragmentary skull materials described by Wieland provisionally under the name of 

 L. angusta (Amer. Jour. Sci., xvm, 1904, p. 184, 185, figs. I, 2) are here made the types of a 

 new species. The carapace which that author has also referred to L. angusta (op. cit., p. 

 187, pis. vi-viii) doubtfully belongs to it. In case the peripheral regarded by Cope as the 

 second really belongs with the type, the carapace described by Wieland certainly does not 

 belong to the species to which he has assigned it, for that peripheral in the type has the border 

 emarginate. Furthermore, the fifth peripheral of L. angusta does not resemble closely any 

 of those of the carapace described by Wieland. It resembles most nearly the fifth of Wie- 

 land's specimen, but differs in relative length and width; apparently also in the position of 

 the pit for the rib. Only future discoveries can decide this point. 



The bones figured by Leidy (as cited in the synonymy) under the name of Chelone sopita 

 have been referred by Cope to Lytoloma angusta. They appear not to agree with any species 

 of Osteopygis in that they are much longer than wide, have the sulci crossing the middle of 

 the length and have the pits well toward the rear end of the bone. 



Lytoloma jeanesi Cope. 

 Figs. 193-195. 



Propleura jeanesii, COPE, Cook's Geol. of New Jersey, 1868 (1869), p. 735 (nom. nud.). 

 Lytoloma jeanesii, COPE, Ext. Batrach., Reptilia, Aves N. A., 1869, p. 145; Vert. Cret. Form. West, 

 1875, p. 257. HAY, Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 452. 



Of this species Cope studied what he regarded as portions of 2 individuals. Of the first, 

 discovered in the upper bed of Cretaceous greensand, near Barnesboro, Gloucester County, 

 New Jersey, there were secured only the nuchal bone and the first peripheral. Cope appears 

 to have lookt upon this lot as the type of the species. Where these bones are now is not 

 known. The second individual was obtained in the same bed of greensand, at Hornersville, 

 New Jersey. This specimen, or most of it, is now in the American Museum, where it has the 

 number 1473. 



The nuchal bone which belonged to the first-named individual was described by Cope as 

 resembling an ordinary peripheral, differing entirely from the nuchal of Chelydra and Chelone. 

 .The anterior border appears to have been obtuse. Its length, from side to side, is not given; 

 the width is stated to have been 16.5 lines (about 34 mm.). The nuchal scute which it bore is 

 said to have been about 18 mm. wide. The bone is described as having joined the first 

 peripheral by a coarse gomphosis, the process coming from the first peripheral. There was 

 also a sutural border for union with the first neural; but we are not told whether or not the 

 nuchal articulated with the first costals. 



The first peripheral is described as having a free inner border, a condition showing that it 

 did not articulate with the first costal. Its suture with the nuchal was straight; that with the 

 second peripheral had the entering angle seen in Osteopygis sopitus, etc. The width of the first 

 peripheral is given as 15.5 lines, about 32 mm. This width was three-fifths of the length, 

 therefore about 53 mm. 



