Jope.] 468 ‘ [Aug. 15, 2872. 
are faced with enamel, but have only smooth cementum without sculpture. 
There are no molars, but the inferior face of the maxillary bone is 
rugose as though alveoli had been absorbed. There are traces of very 
shallow alveoli. 
The cast of the brain indicates smooth oval hemispheres which leave 
the cerebellum and olfactory lobes entirely exposed. The latter are ovoid 
and expanded laterally. 
The cranium is depressed, and has a trace of interparietal crest. The 
anterior margin of the temporal fossa is marked by a curved angle on 
each side of the frontal bone. The supra-orbital arch is very short. 
This curious animal reminds me of asmall Megalonyw with flattened 
cranium. The cutting teeth above are, however, more like those of 
rodents. 
M. 
Denoth: cranium (8.0106). 6. 6. ve isis ses Sura eas ...0.090 
Width Coe (WAUHOUn Ay ROME ds s/n salve cence or) 040 
i “near end of nasals..:.... Poe ioe Corin’ Carlie 
Go UPDer CuutinO LOGI ga. a1... HOA Y GAGS fone ny oO 
Depth bad o TS alas Pade WOE Vn bags UUDD 
Length exposed part lower tooth........ Veneeee gn ONG 
Width Gs ies eS Pe ee ee 006 | 
Gen. et sp. nov. 
This is a genus of true Testudinida, designed to include those with 
double anal scuta, and posterior lobe of the plastron bifurcate. In addi- 
tion to the species above named, the HZ. quadratus (Testudo hadriana, 
Cope), and probably the species to which belongs a small piece named by 
Leidy, 7. corsont, pertain to the genus. 
The ZH. octonarius is distinguished from its congener in many ways. 
It is of elongate form, strongly contracted at the bridges, but expanded 
and arched above the limbs. The carapace in quite convex. The plas- 
tron has the posterior lobe emarginate rather than bifurcate, as seen in 
H, quadratus. Fach projection represents a right-angled triangle rather 
thana wedge. The anterior lobe presents an elongate lip, which is ex- 
panded, and slightly emarginate at the end. The mesosternal bone is 
heart-shaped, the posterior emargination being wide and deep. 
The anterior margin of the carapace is somewhat flared above the 
limbs. The nuchal scutum is very narrow transversely, but elongate. 
The carapace descends and is incurved in the middle of the posterior 
margin. 
eer 
M. 
Wbensth (below). ........... Wie aio en eee Utica pirat 730 
Width at middle...... wihey ce ie eta oa Apa oe 5 4. 
7 ean, Ss. 6. Sree Pole oee eee Fee Geile: 525 
This species differs from the H. quadratus in many important points. 
It is perhaps the largest of our extinct land tortoises, and is founded on 
a beautifully perfect specimen from the bluffs of Cottonwood Creek. 
