308 FOSSIL TURTLES OF NORTH AMERICA. 
‘This formation is placed by Lapparent at the base of the Oligocene. The specimen is a very 
imperfect one, and it may be said that the genus is only approximately determinable. Dr. 
A. E. Andrews (Surv. Dept., Pub. Works Ministry, Geol. Surv. Egypt, 1903; Catalogue Tert. 
Vert. Fayum, Egypt, 1906, p. 278, plate xxiv) has described a land-tortoise from the Upper 
Eocene of Egypt to which he has given the name Testudo ammon. If a true Testudo, it is the 
oldest known. The publisht figures show that the neurals are variable in form, but the relation- 
ships to typical Testudo are so close that it may be accepted as belonging to this genus. In 
some respects it appears to be intermediate between Testudo and Hadrianus. 
The oldest known representative of the family is Hadrianus majusculus, of the Wasatch 
beds of New Mexico. 
The following table presents a list of the North American fossil species belonging to the 
Testudinida so arranged as to exhibit their geological sequence: 
Species. 
Equus, or 
Pleistocene. ee 
| Sheridan beds. 
Testudo hexagonata, T. Jaticaudata, T. atascose (Texas). 
Testudo crassiscutata (Florida). 
Peace Creek. 
Pliocene. — 
| Blanco. Testudo pe rtenuis, T. turgida, T. campester (Texas). 
mecnids klettiana, T. undata (New Mexico); T. niobrariensis, T. Sholland® T. edz | 
Loup Fork (Nebraska); T. impensa (Montana); T. gilberti, T. orthopygia (Kansas); T. 
arenivaga (Nebraska). 
Miocene: Deep Rica: Testudo pansa, T. osborniana (Colorado); T. arenivaga (Nebraska); T. emiliz (South 
and Dakota). 
Pawnee Creek. Testudo vaga (Wyoming); ?T. peragrans, T. farri, T. inusitata (Montana). 
John Day Stylemys conspecta, S. capax (Oregon); S. RARE (California: 
Oligocene. White River. 
Testudo brontops, T. thomsoni (South Dakota); ?T. peragrans (Montana); T.ligonia, 
T. cultrata, T. laticunea, T. amphithorax, T. quadrata (Colorado); 
(Assiniboia); Stylemys nebrascensis (South Dakota, North Dakota, Nebraska, 
T. exornata | 
Wyoming). 
Unita. | Hadrianus turidus (Utah). - 
Jackson. Rdnaaue schucherti (Mississippi). 
Eocene. Bridger. Hadrianus aaa non Achilemys allabiata (W yoming). 
Wasatch. Hadrianus majusculus (New Mexico), H. corsoni? (New Mexico: 
Puerco. 
We can not doubt that the predecessors of Hadrianus will yet be found in the Puerco beds 
or their equivalents. We may even look confidently for more primitively constructed Tes- 
tudinidz in some of the Upper Cretaceous deposits. They are more likely to occur in river 
valley formations or zolian accumulations. 
Considering the large size of Testudo brontops, the grade of its differentiations, and the 
great number of species “ol T estudo which made their appearance in the Oreodon beds of the 
Oligocene we may be sure that species of the genus will yet be discovered in some of the upper 
fernations of the Eocene of America; as they have already been found in the Upper Eocene 
of northern Africa. 
Nevertheless, it seems to the writer that the family was, in the earlier half of the Eocene, 
in a stage of development represented by Hadrianus corsoni of the Bridger, and that Testudo 
ee with its only slightly differentiated costal plates, represents a stage which existed 
possibly even in the Upper Eocene. It may be concluded therefore that any members of the 
family that shall be found in the Puerco and Upper Cretaceous will display further approxi- 
mations to the Emydidz. 
It will be interesting to consider in the light of knowledge derived from both the living and 
the fossil species of the family the special chame ters which they have dev elopt since shee first 
appearance: as we might say, the goal toward which they have been striving. 
With regard to the shell we see that it is usually very high and convex. ‘There are various 
exceptions to this statement; nevertheless, we find no species so deprest as some of the Emy- 
didz; and the height and convexity will average much higher than among the species of the 
