304 FOSSIL TURTLES OF NORTH AMERICA. 
mm. on the fourth costal and 6.5 mm. on the fifth. This indicates that these vertebrals were 
very narrow, probably about 30 mm. 
No. 1181 has a label in Cope’s handwriting which indicates that it is a portion of his 
principal specimen (Vert. Tert. Form. West, p. 134), but only a part of the bones described is 
present. Among these are portions of both the costals of the first pair. On the inner surface 
of each is a sutural scar for articulation with the axillary buttress. This is 5 mm. wide and on 
one of the pieces it is 17 mm. long, while the original length has been still greater. On page 
143 of his Vertebrata of the Tertiary Formations of the West, Cope refers to certain bones 
which he had formerly described as xiphiplastrals and as showing that the pubis had articulated 
with the plastron. With this lot of bones is a rough drawing made by Cope which represents 
one of these costals as a part of the plastron. The bone (fig. 384) is, however, without doubt 
a costal, as Cope himself came to suspect. ‘The outside of this costal shows strong concentric 
grooves produced during the growth of the first costal scute. 
With the bones just described is what appears to be one of the hinder neurals. It is 16 
mm. long, 17 mm. wide, and 7 mm. thick. The outer surface is rather rough. A fragment of 
the plastron, probably shen its center, is g mm. thick. The right free border of the hypo- 
plastron is represented by a fragment 23 mm. long. The edge is subacute. From this the bone 
thickens rapidly to the inner border of the beveled surface on the upper side, where it is 9.5 
mm. thick. This surface is 15 mm. wide and is bounded interiorly by a sharp groove. 
Fics. 384-386.—Echmatemys testudinea. Costal and plastral bones. 
384. Distal end of right first costal, inner surface. 2. No. 1181 A.M.N.H. Shows scar for axillary buttress. 
385. Mesial portion of right hyoplastron. 4. No. 1179 A.M.N.H. 
386. Free border of hypoplastron, with section (a) at articulation with xiphiplastron. 4. No. 1179 A. M.N.H. 
No. 1179 may or may not all belong to the same individual, and the bones are probably 
another portion of Cope’s principal specimen. The right hyoplastron (fig. 385) measures on 
the midline 46 mm. At the midline and where it joined the hypoplastrals the thickness is 13 
mm., and 12 mm. where it joined the entoplastral. The femoro-abdominal sulcus crosses 33 
mm. behind the entoplastron. The humero-pectoral sulcus can not be distinguisht. A frag- 
ment of the epiplastron has the free edge rather acute. The beveled surface is 16 mm. wide 
and has a maximum thickness of g mm. Fig. 386 represents the upper surface of the left free 
border of the hypoplastron and a section at the hypoxiphiplastral suture. The beveled area 
has a width of about 20 mm. and at the summit the bone is 13 mm. thick. It is limited on the 
inner side by a sharp groove. The beveled surface shows grooves produced by the scute—the 
femoral. A fragment of the left xiphiplastron shows that this was only 36 mm. long on the 
midline. There was evidently a posterior notch. At the anterior end of the median suture the 
thickness of the bone is 8 mm.; posteriorly it thins down to 4 mm. 
No. 1179 includes likewise the proximal half of a costal, almost certainly the sixth of the 
left side (plate 45, hg. 17). The upper surface presents an elevation outside of the costo- 
vertebral sulcus, as in the case of those previously mentioned. Anteriorly this sulcus is removed 
6 mm. from the neural border, but posteriorly it has receded to a distance of 13 mm. This 
indicates that the fourth vertebral expanded where the sulcus down the sixth costal departed. 
