344 FOSSIL TURTLES OF NORTH AMERICA. 



The figure itself is incorrect. His fig. 21 is that of a bone J mm. long and 8 mm. wide. The 

 bones figured indicate a turtle which had a carapace about 100 mm. long. The originals of 

 Cope's figs. 20, 21, and 22 are in the U. S. National Museum. We are not informed by that 

 writer whether or not these bones belonged to a single individual. If they do, his fig. 21 repre- 

 sents the seventh neural and his figure 20 the eighth. Cope's fig. 22 represents a peripheral. 

 In its upper border there is a pit for the end of a rib. The fore-and-aft extent of the bone is 



9 mm. Its free border is broken away, but the height of the bone was somewhat more than 



10 mm. It is considerably recurved. Its thickness is between 3 mm. and 4 mm. The sulci 

 crossing it are broad and rather deeply imprest. 



Palaeotheca terrestris Cope. 



Palteotheca terrestris, COPE, Palaeont. Bull. No. I, 1872, p. 464; Proc. Amer. Philos. Soc., XII, 1873, p. 464. 

 Emys terrestris, COPE, Sixth Ann. Report U. S. Geol. Surv. Terrs., 1872 (1873), pp. 625,629; Vert.Tert. 



Form. West, 1884, pp. 129, 130, 131, plate xviii, figs. 23-25. HAY, Bibliog. and Cat. Foss. Vert. 



N. A., 1902, p. 448. 



Of Cope's specimens of this species, three in number, those parts represented by his 

 figs. 23, 24, and 25 of the plate cited are in the U. S. National Museum and have the number 

 2107. All his materials were found in Bridger strata, but the exact locality and level are 

 nowhere mentioned. They were undoubtedly secured somewhere in the region about Fort 

 Bridger, Wyoming. 



Of his type specimen Cope figured I neural, I costal, and the right epiplastron. In his 

 description he probably intended to give the measurements of the neural figured. At any rate, 

 there is some error, for it is not probable that any neural was twice as wide as long. The neural 

 figured is 9 mm. long and 13 mm. wide. The width of the costal is given as 1 1 mm., whereas 

 the width of his figure 25 is only a little more than 10 mm. 



This species is stated by Cope to differ from P. polycypha in having bones at once larger 

 and thinner; and this is confirmed by a comparison of the neurals of the two species, as they 

 are figured. As in the case of P. polycypha, there was a dorsal carina, and this was interrupted 

 by the deeply imprest scutal sulci which crost it. 



The epiplastron is 19.5 mm. long and 18 mm. wide. The lip projected abruptly from the 

 general outline about 3 mm. and was truncated. The anterior edge was acute. At its base the 

 lip was 21 mm. wide and nearly as wide in front, the width of the half of it present being 10 mm. 

 On the upper side of the lip the bone was thickened backward for a distance of about 1 1 mm., 

 the greatest thickness being 4.5 mm. 



Cope's fig. 25^ gives a view of the hinder articular border of a costal. This is 3 mm. thick 

 at the proximal end of the bone, but at the lower end is 5 mm. This costal appears to be the 

 fifth of the right side; and with the succeeding one formed a ridge for the inguinal buttress. As 

 shown by Cope's fig. 250, at the lower end of the bone and at its hinder border there was the 

 half of an excavation for this buttress. About the distal half of the costal is broken away and 

 the buttress therefore ascended one-half the height of the costal. The rib-head is hardly dis- 

 cernible. The proximal end of the costal does not join accurately the neural of Cope's fig. 23; 

 hence it is concluded that this neural is the third. The costo-vertebral sulcus (Cope's fig. 25) 

 crosses the costal at a distance of 5 mm. from the proximal end, from which fact it is concluded 

 that the fourth vertebral scute was about 28 mm. wide. The turtle was undoubtedly a small 

 one with a thick, heavy shell. 



Cope states that the articulations of the bridge with the costals were not known to him. 



No specimens belonging to this species or to P. polycypha were secured by the expedition 

 from the American Museum of Natural History into the Bridger beds in 1903. 



Genus HYBEMYS Leidy. 



Insufficiently known emydoid turtles, the upper surface of whose peripherals was orna- 

 mented by a row of hemispherical bosses, each of which was crost by the suture between the 

 two peripherals on which it rested. 



Type: Hybemys arenana Leidy. 



