TRIONYCHIDA. 499 
The neurals are relatively broad. The accompanying table shows their dimensions. 
It is not certain that the outlines of 
the seventh neural are correctly drawn in 
the figure; but they appear to be as shown. 
If so, this neural is of unusual form and size 
for the posterior one. It did not wholly 
separate the costals of the seventh pair at 
the midline. 
Neural. Length. Width. 
rar 
5 
4 19 18 
5 17 | 
6 
5 | 3 
The central portions of the upper sur- 
face of the carapace are nearly smooth. 
Gradually toward the outer borders a 
sculpture appears. On a band about 35 
mm. wide around the borders this sculp- 
ture is quite distinct and consists of ridges 
separated by furrows and pits. These 
ridges run nearly parallel with the free bor- 
ders of the carapace. The furrows are usually narrower than the flat-topped ridges. A line 
10 mm. long crosses four of the ridges. 
Nassau, an old name for Princeton University. 
ee 
Fic. 653.—Aspideretes nassau. Carapace of type. 
0.35. Partly restored. 
Aspideretes puercensis sp. nov. 
Plate 94, figs. 1-3; plate 104, figs. 2, 3; text-figs. 654, 655. 
This species is represented by a single specimen, which belongs to the American Museum 
of Natural History, and bears the number 1202. The right side of the carapace is nearly com- 
plete, lacking only the eighth 
costal and the free ends of 
most of the ribs; and there 
are present large portions of 
the left side of the plastron. 
All these parts belonged to a 
single individual, which was 
collected by Dr. J. W. Wort- 
man and Mr. O. A. Peterson, 
in 1892, in the Puerco beds 
of New Mexico, probably in 
the southern part of Rio 
Arriba County. 
Up to the present time, no 
Fics. 654 AND 655.—Aspideretes species of Trionychide has 
puercensis. X4. been described from the 
Puerco Eocene except Con- 
chochelys admirabilis Hay. 
Professor Cope has credited 
(Proc. Amer. Philos. Soc., 
xx, p. 461) to the Puerco deposits the Wasatch species Plastomenus communis, but it was 
with a doubt, and the species was not included in later lists. Nor is it mentioned in Cope’s 
Vertebrata of the Tertiary Formations of the West as belonging to the Puerco. 
654. Carapace. 655. Plastron. 
