DERMATEMYDID&. 231 
lower surface of the plastron; at the femoro-anal sulcus, only 20 mm. On the upper surface 
of each xiphiplastron is a scar for the pubis. This scar is 55 mm. long and 30 mm. wide. 
The inner borders of the two are 100 mm. apart. The hinder end of the lobe is truncated 
and bent upward as the hinder extremity is approacht. 
The median portion of the plastron is very concaye, a condition which appears to indicate 
that the individual was a male. 
On some parts of the plastron the sulci bounding the epidermal scutes are very distinct; 
in others they are obscure, but determinable. They consist of very narrow, thread-like grooves, 
some of which pursue their course at the bottoms of broad channels, while others keep on 
the level of the general surface. The median sulcus runs an extremely irregular course, being 
first on one side of the midline, then on the other. The intergulars occupy the whole lowe: 
surface of the lip, extending backward 100 mm. along the midline. The gulars meet at the 
midline a distance of 35 mm. Their posterior borders run parallel with the anterior. 
At the midline the humerals join for a distance of only 8 mm.; but from this they expand 
rapidly and their outer ends reach about 60 mm. behind the axillary notch. The pectoral 
scutes are, fore and aft, extremely broad, meeting along the midline a distance of 195 mm. 
Their outer ends are only 30 mm. wide. The abdominal scutes extend along the midline 160 
mm., while their outer borders are 240 mm. long. The length of the femorals at the midline 
may be taken as go mm.; that of the anals as the same. 
The scutes covering the bridge are separated from the plastral scutes just described by a 
nearly straight sulcus running from the axillary to the inguinal notch. Of these scutes the 
most anterior and the posterior alone appear to represent the inframarginal series. The 
others are bridge marginals. Of these, one, the sixth marginal, has become greatly expanded 
at the abdominal end; the other marginals are greatly narrowed at their lower ends. ‘This 
absence of a series of inframarginals is remarkable in this family. 
The sculpture of this species resembles closely that of its predecessor, B. variolosa. The 
carapace and the plastron are both rough with sharp elevations, which are usually triangular 
pyramids. These are mostly arranged in rows, of which three or four are spanned by a line 
to mm. long. 
The present species differs from B. variolosa in various points. The gulars of the Judith 
River species are crowded far from the median line; in B. sinuosa they are in contact with 
each other. The pectoral scutes of B. sinuosa extend backward nearer to the hyohypoplastral 
suture than they do in B. varrolosa. The hinder extremity of the plastron of B. sinuosa is trun- 
cated, bent upward somewhat, and has its borders acute; that of B. variolosa is broadly 
rounded, flat, and the borders are thick and obtuse. From some peripherals present, belonging 
to the type of B. variolosa, it appears that the sculptured, horn-covered surfaces on the under 
side of the peripherals are considerably broader than they are in B. smmuosa. On the eighth 
peripheral this surface is 70 mm. wide; in B. sinuosa it is only 50 mm. wide. The plastron 
of the type of B. variolosa is only about 10 mm. longer than that of B. snuosa Riggs. 
A fragment of the epiplastral lip of what is regarded as this species was found by Mr. 
Barnum Brown of the American Museum, on Hell Creek, Dawson County, Montana. 
Basilemys imbricaria (Cope). 
Plate 32, figs. 5, 6, 7; text-figs. 290, 291. 
Compsemys imbricartus, Cope, Proc. Acad. Nat. Sci. Phila. 1876, p. 257; Bull. U. S. Geol. Surv., m1, 
EH By SIS an er ox 
Basilemys imbricarius, Hay, Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 445.—Hatcuer, Bull. U.S. 
Geol. Surv. No. 257, 1995, p- 77- 
Adocus (Bastlemys) tmbricartus, OsBoRN, Cont. Canad. Palzont., 111 (4to), 1902, p. 16. 
This species was founded by Professor Cope on very unsatisfactory materials. The type, 
to which only three fragments (No. 6102 of the American Museum of Natural History) can be 
referred with any certainty, was found in the Cope collection mingled with fragments of two 
or three other species. The identified bones are here figured of the natural size (plate 32 
figs. 5, 6, 7). All are probably portions of costal plates. The larger piece is traverst by a 
narrow and sharply imprest sulcus, and appears to be the fragment mentioned by Cope as 
