PLASTOMENID~&. 4 
~ 
w 
Plastomenus corrugatus Cope. 
Plate 86, fig. 5. 
Plastomenus corrugatus, Core, Syst. Cat. Vert. Eocene New Mexico, 1875, p- 35; Append. LL of Wheeler’s 
Report to Chief of Engineers, 1875, p. 1016 (of separata, p. 96); Wheeler’s Surv. W. rooth Merid., 
Iv, pt. 11, 1877, pp. 48, 50, plate xxv, figs. 20-26; Vert. Tert. Form. West, 1884, p. 123.—Hay, 
Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 452. 
Professor Cope stated in his monograph on the fossil vertebrates of New Mexico that he 
had remains of 6 individuals which he referred provisionally to the present species. Of these 
he figured fragments of 2. One of these two was represented by only a portion of the left 
hypoplastron; and this was regarded as the type of the species. It is represented by his fig. 20, 
which is here reproduced (plate 86, fig. 5). The other bones figured were portions of costals 
except the one represented by his figure 25. The present writer is not aware where these hgured 
specimens now are. They were collected in the Wasatch beds of New Mexico. The exact 
locality was not designated, but it was doubtless from the Gallinas River region. 
Of the type bone, the hypoplastral, Cope makes the following statements: 
This bone is ornamented with sharp, raised, narrow ridges, which are straight or vermiculate, and 
which inosculate but little. The broken base of the bridge is particularly stout, and the thickening 
continues within the inguinal border to the postabdominal extremity. The inguinal edge is thinner, and 
is incurved at the postabdominal gomphosis. 
MEASUREMENTS. 
Meter. 
Thickness of the hyposternal at middle. . 0.007 
Thickness of hyposternal at bridge. . 009 
Seven ridges measure... . ; -O10 
Judging from Cope’s figures of the costal bones, they presented a very different style of 
ornamentation. Here we find what Cope has called a honeycombed structure. There were 
apparently abruptly sunken pits, about 5 in a line 10 mm. long; while the intervening ridges 
were about as wide as the pits themselves. Professor Cope presented no measurements of these 
bones, so that we do not know their thickness. Altho they are so different in their style of 
ornamentation from the type plastral bone they appear to be connected with it by the bone 
represented by Cope’s fig. 25. Cope regarded this bone as a part of the left hyoplastron; but 
a comparison of it with the plastron of Plastomenus thomas: makes it more probably the outer 
end of the right hyoplastron. The figure ought to be inverted. 
Plastomenus communis Cope. 
Plate 86, figs. 6-8. 
Plastomenus communts, Cope, Syst. Cat. Vert. Eocene, New Mexico, 1875, p. 35; Append. Li of Wheeler’s 
Report to Chief of Engineers, 1875, p. 1016 (of separata, p. 96); Wheeler’s Surv. West tooth Merid., 
Iv, pt. 11, 1877, pp. 48, 50, plate xxv, figs. 1-3, ?4; Vert. Tert. Form. West. 1884, pp. 123, 126.— 
tay, Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 452- 
That specimen which 1s represented by fig. 1, plate xxv, of Cope’s memoir publisht in the 
fourth volume of the Wheeler Survey, must be regarded as the type of the present species. 
This type belongs to the U. S. National Museum and bears the catalog number 1132. It con- 
sists of the distal ends of a number of costal plates and a portion of the left hyoplastron. These 
were collected by Professor Cope in Wasatch beds in New Mexico, doubtless in the region 
of the Gallinas River. 
While the known remains of this turtle indicate a distinct species and one which may be 
recognized when other considerable parts shall have been discovered, they do not enable us 
to obtain an accurate idea of the animal. It must have attained a considerable size, since one 
of the costals had a width of 44 mm. It had a thick and coarsely sculptured shell (plate 86, 
figs. 6,7). There were no rib-ends protruding beyond the borders of the carapace. The form 
of the fragment of the hyoplastron (plate 86, fig. 8) present indicates pretty certainly that the 
species belongs to the genus Plastomenus. 
