232 FOSSIL TURTLES OF NORTH AMERICA. ° 
having the direction of the ridges of sculpture running at nght angles with the sulcus. The 
inner ures of the bone is removed, so that the dhichaess oF the fragment can not be deter- 
mined. It was more than 6 mm. 
The piece of medium size has a sutural edge along one side. ‘The thickness is 6 mm. 
where thickest, 5 mm. where thinnest; and it may be the fragment whose measurement Cope 
gave. The smallest piece of bone is only 3 mm. thick. 
This species is distinguisht especially by its sculpture. It is thus described by Cope: 
It consists, in the Compsemys imbricartus, of excavations bounded on the sides by a short ridge 
each, which [excavations] alternate with each other. Thus each bounding ridge terminates abruptly 
at the fundus of one of the fosse, while the other end of the fossa rises and contracts into another 
ridge. The result is precisely that seen in the interior sculpture of Saracenic domes and niches, 
and is one quite unique among tortoises. The direction of the ridges is at right angles to the costal 
dermal sutures. 
Cope states that three of the fossae measure in length 6.5 mm. and crosswise, 5mm. Inthe 
case of the largest of the three fragments of the type three foss taken together measure 7 mm. 
and crosswise, 6 mm. 
While this style of ornamentation appears to be very peculiar, something scarcely dis- 
tinguishable in pattern may be seen here and there on the carapace of B. variolosa, and for 
that reason the present species has been referred to Basilemys. In fact Cope has jabeled as 
Compsemys imbricaria some fragments the sculpture of which appears quite identical with that 
of B. vartolosa. With these eter fragments, however, there is what seems to be the thickened 
rim of the front of the carapace (fig. 290, No. 6100 A. M. N. H.), and this is plainly different 
from that of B. variolosa. Evidently there is another species occurring with B. variolosa, 
related to it, but differing in important characters. For this species we may for the present 
retain the name Basilemys imbricarta. 
The remains of this form were collected in 1876, in the Judith River beds of Montana, by 
Mr. Charles H. Sternberg. 
Fig. 290 represents a section across the supposed anterior peripheral, No. 6100 A. M. N. H. 
The part of this peripheral which joins the costal 
is missing. On the under side it appears to extend 
pecan to the line reacht by the soft skin, a 
distance of 27 mm. from the free border. The 
extreme thickness of the fragment is 16mm. The 
upper surface is slightly convex; the lower surface 
strongly so. The ornamentation is coarse, there 
Sections. 3. No. 6101 A. M.N.H. being 3 fossein g mm. This peripheral differs from 
2go. Section across peripheral. one in the same region of B. variolosa in having 
291. Section across border of xiphiplastron. C : - 
the sculptured surface on the under side of the bone 
much narrower from the free edge to the skin line in proportion to the thickness of the bone. 
It is to be noted that these ‘coarsely sculptured fragments possibly do not belong to B. 
imbricaria. 
In the Cope collection there is another fragment (No. 6101) which possesses a sculpture 
like that of the specimens just described, and this is evidently a portion of the left xiphiplastron 
(fig. 291). There are 3 fosse in 8 mm. It differs from that of B. varrolosa in having a sharp 
border separating the lower surface from the surface which looks outward and upward. In 
B. vartolosa the lower surface of the hinder lobe rounds gradually into the upper surface. 
Professor Cope has labeled as Compsemys aye) aria other specimens from the Judith 
River beds which have a sculpture similar in pattern but much more delicate. In these 
(No. 6103 A. M. N. H.), some of them fragments of costals, there are 4 fossa in a line 5 mm. 
long. The scutal sulci are thread-like. Orier fragments, peripherals from the bridge perhaps, 
cae similar ornamentation but the sulci are very broad. It seems very probable that the 
fragments here described belong to more than one species, but the discovery of additional and 
much better materials will be required in order to determine the structure and generic position 
of Cope’s Compsemys imbricaria. 
201. 
Fics. 290 AND 291.—Basilemys imbricarta. 
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