472 



FOSSIL TURTLES OF NORTH AMERICA. 



Plastomenus? lachrymalis Cope. 

 Plate 86, fig. 3. 



Plastomenus lachrymalis, Cope, Append. FF, Ann. Report Chief of Engineers, 1874, p. 603 (of separata, 

 p. 96); Syst. Cat. Vert. Eocene N. Mex., 1875, p. 35; Wheeler's Surv. W. 100th Merid., iv, pt. II, 

 1877, pp. 48, 51, plate xxv, figs. 7-76; Vert. Ten. Form. West, 1884, p. 123. Hay, Bibliog. and 

 Cat. Foss. Vert. N. A., 1902, p. 452. 



This insufficiently known species was secured by Cope in the Wasatch deposits of New 

 Mexico. It was based on a single individual and apparently on only fragments of costal plates. 

 Of these 2 were figured. These remains were evidently referred to Plastomenus because ot 

 the character of the sculpture. We can not be sure of the correctness of this assignment before 

 similar costals shall have been found associated with the plastral bones. The writer does not 

 know where the specimen now is. 



Professor Cope's description is given below, and one of his figures, that of the distal end 

 of a costal bone, is reproduced on the plate referred to above. The part of the figure indicated 

 by a shows the thickness of the bone. 



Costals with finer pits [than in P. sertalis], the welts broken into tubercles posteriorly. 



The largest species of the genus represented in the Eocene of New Mexico. The costal bones are 

 rather finely punctate, the posterior as well as the anterior. The anterior costal bones are crossed by 

 numerous ridges from side to side obliquely; the obliquity increasing posteriorly. On the posterior 

 bones they are broken into vertical bars, separated by considerable intervals, and of linear form. The 

 posterior costals reach a thickness of 0.006 m. and a width of 0.025 m - 



The pitting of the posterior part of the carapace distinguishes this species from the P. wdenuus. 



But one specimen obtained. 



Plastomenus? fractus Cope. 



Plate 86, fig. 4. 



Plastomenus fractus, Cope, Syst. Cat. Vert. Eocene New Mexico, 1875, p. 35; Append, ll of Wheeler's 

 Report to Chief Engineers, 1875, p. 1016 (of separata, p. 96); Wheeler's Surv. W. 100th Merid., 

 iv, pt. ii, 1877, p. 49, plate xxv, figs. 12-19; Vert - Tert - t" orm - West > l88 4, P- 123. Hay, Bibliog. 

 and Cat. Foss. Vert. N. A., 1902, p. 452. 



The types and all other specimens of this species having apparently been lost, the present 

 writer must content himself with reprinting Cope's description and one of his figures. It 

 maybe said, however, that there is nothing about the specimens or the description that either 

 confirms or disproves the correctness of the reference of the species to the genus Plastomenus. 

 Important parts of the plastron are needed for the settling of this question. The species 

 comes from the Wasatch beds of New Mexico; but the exact locality was not given by Cope. 

 It was, however, from the region of the Gallinas River. 



Five individuals in a fragmentary condition represent this turtle, and present greater uniformity of 

 character than some of the others. The sculpture is a honeycomb, where the fossae are wider than the 

 separating ridges, [and] which is traversed at intervals of two or three fossae by elevated lines, which are 

 transverse or oblique to the long axis of the costal bones as they are situated in the carapace. These 

 lines are elevated portions of those separating the fossa?, and hence differ entirely from the smooth, thick 

 welts of the species of the genus which follows. They are usually zigzag in their course, as defining the 

 pits, and sometimes inclose small pits. The vertebral bones are strongly pitted. None of the specimens 

 indicate large size. 



Measurements. 



Meter. 



Width of a vertebral bone 0.012 



Width of a costal bone 22 



Thickness of same 005 



Interval between two raised lines 007 



Plate 86, fig. 4, is reproduced from Cope's work of 1877, cited above. The figs. w and \ 

 represent the outer and the inner surfaces of the proximal end of a costal. Figs, y and 2 show 

 middle parts of costals. It is greatly to be desired that far better specimens of this and other 

 Wasatch species ot turtles, so otten based on fragmentary specimens, shall soon be found. 



