384 FOSSIL TURTLES OF NORTH AMERICA. 
was obtained by Professor Cope in the neighborhood of Cottonwood Creek, Wyoming, and 
comes from the Bridger Eocene beds, the level being that known as B. 
Cope’s description of this species is very brief and unsatisfactory, not even doing justice 
to the fragmentary materials at his command, yet including statements that imply that he 
had more materials than are now accessible. He states that the plastron was concave, yet we 
have no evidence that other parts of it were present than the half of the anterior lobe. The 
surface of the carapace is said to be without irregularities of surface, yet no neurals or costals 
seem to have been secured. 
The size of the individual must have been greater than estimated by Cope. He says that 
the length was 18 inches, equal to 437 mm. Cope’s fig. 14 of his plate represents the ninth, 
tenth, and eleventh peripherals of the right side, and about half of the pygal. The length of 
the ninth and tenth taken together amounts to 156 mm. The length of the same two elements 
of a specimen of H. corsoni whose carapace has a length of 5g0 mm. is 131 mm. An estimate 
based on these dimensions makes it probable that the type of the species had a length of about 
626 mm., or about 25 inches. 
It is improbable that this species belongs to the genus Hadrianus. Two reasons may be 
assigned for this opinion. The first is found in the fact that there is no epiplastral lip, a 
485. 
Fics. 482-485.—Achilemys allabiatus. X%. Type. 
482. Portion of rear of carapace. per. 11, eleventh peripheral; py, pygal; spy, suprapygal. 
483. Portion of anterior lobe of plastron. hyo, hyoplastron; ent, entoplastron; eps, epiplastron. 
484. Section of ninth peripheral. 
485. Section at anterior end of eleventh peripheral. 
structure found in the other species of the genus, except possibly in H. tumidus, the only known 
specimen of which does not present that region. In Achilemys allabrata this lip is not differ- 
entiated even so much as it is in the Emydide. 
The second reason is found in the structure of the hinder region of the carapace. With 
the other bones of this species at Washington there is a portion of a suprapygal which joins 
accurately the eleventh peripheral and the pygal of the type. This is represented in its proper 
position in fig. 482. This bone has the position of the third suprapygal of Testudo and of 
Fladrianus corsont. In the genera just named the sulcus between the last vertebral scute and 
the supracaudal scute Fallows closely the suture between the third suprapygal and the pygal. 
In the species being here described the sulcus crosses the suprapygal at some distance above 
the suture rereieede to. It is to be noted also that the three peripherals of this region are 
traverst by perpendicular sulci from top to free border, showing that the sulcus between the 
marginal scutes and the costal scutes ran on or above the sutures between the peripheral and 
costal bones. The position of the sulci of this region in our species resembles somewhat that 
of Kachuga, as represented by Mr. Boulenger (Cat. Chelonians, p. 53, fig. 16). 
The epiplastron (fig. 483) figured by Cope has the anterior end thickened and rounded 
in section. More posteriorly this. epiplastron has an acute border. At their symphysis the epi- 
plastra have a thickness of 23 mm. ‘The truncated end of the anterior lobe, the rudimentary 
lip, has a width of about 125 mm. The scute-covered area on the upper surface is 18 mm. 
wide. The bone on this surface does not thin backward as in Testudo and Hadrianus. The 
entoplastron had a width of about 170 mm. It was truncate or cordate behind, notwith- 
