284 
TESTUDINATA. 
bridge is thin and the axillary borders are thickened, but not prominent 
inward. The end of a mesosternal bone is rather produced, and has not the 
lateral expansion seen in some Testudines and Stylemys nehrascensis and S. 
niobrarensis. A costal bone of uncertain specific reference, is abruptly ex¬ 
panded at the proximal end, indicating the narrowing of the adjacent one. 
Its proximal end is transversely truncate, and on the inferior side is a slightly 
elevated and compressed capitulum, whose long axis is in that of the costal 
bone. The costo-vertebral scutal suture at the intervertebral scutal suture 
is but little inflected; the intervertebral is straight. 
A vertebral bone picked up alone, is wider than long; its form is sub¬ 
quadrate, with truncated angles and concave sides. The superior surface 
is smooth; on the middle line of the inferior is a longitudinal thin lamina, 
well produced downward, for suspension of the vertebra, resembling the 
arrangement I have shown to exist in Stylemys. This bone belonged to a 
tortoise of large size. It measures, length, O^.OTh ; width, 0™.090; thick¬ 
ness, 0™.013. In all the marginal bones preserved, they are seen to be united 
with the costals by a squamosal suture, and in no instance by gomphosis. 
The specimen which furnishes the characters of the Testudo undata 
includes portions or wholes of eight marginal bones and one costal. The 
former display a strong recurvature outward, and their internal thickening 
is near their sutural union with the costals. The borders are acute and do 
not display any emargination at either the dermal or osseous sutures. The 
posterior part of the margin of the posterior marginals is very convex or 
flared upward, descending at or behind the osseous suture. Thus the fore 
edge has an undulating form. The caudal marginal bone is recurved, not 
prominent, and with a regular entire free margin. Its lateral sutures ex¬ 
pand forward, so that its margin is narrower than its anterior portion. It is 
not divided by a dermal suture, consistently with the generic character. The 
surfaces of the bones are nearly smooth. The scutal sutures are wide, and 
have distinctly-defined borders. The marginal near the bridge is remark¬ 
ably massive, the bridge ward suture being twice as thick as that joining the 
free marginal. 
The size of the Testudo undata is as great as that of any of the species 
of Land-tortoises of our Tertiary formations. 
