TESTUDINATA. 769 



No. 2. 



U. 



Width of lip 089 



Width of mesostemnm 103 



Length of mesosternum 096 



Width of anterior lobe at base 210 



Length of anterior lobe (axial) 125 



Thicknees of a costal bone 080 



Head of Horse Tail Creek, northeast Colorado. 



STYLEMYS Leidy. 



Cope diagnosis, Transactions Amer. Philos. Society, XIV, 1866, p. 123. 



This genus probably belongs to the Emijdidce, in the neighborhood of 

 Manuria, now existing in Eastern Asia. It is characteristic of the American 

 lacustrine Miocene, but is represented by very few species. 



Stylemys nebrascensis Leidy. 



Report U. S. Geol. Surv. Terrs., I, p. 224, 1873. Proceed. Acad. Phila., 1851, p. 172. Testiido hemit- 

 pherica, T. oweni, T. ciilbersom, and T. lata, Ancient Fauna Nebraska, 1853, 105-110. PI. XX-XXIV. 



I obtained this species in Northeastern Colorado, in the White River 

 formation, with the Tortoises already referred to the genus Testudo. Some 

 of the specimens are of large size, others small. I have also numerous 

 well-preserved chelonites from the John Day River beds of Oregon, 

 which I refer to the same. Many of the Oregon specimens differ in some 

 respects from the typical forms of the S. nebrascensis, but the characters are 

 not constant. I observe three principal characters of the smaller and 

 medium-sized specimens from Oregon. These are, first, the greater trans- 

 verse length of the first marginal dermal scutum. This is caused by the 

 more external position of its external bounding suture ; instead of being 

 nearly continuous with the lateral suture of the first vertebral, it is some 

 distance external to it. This I find in all the Oregon specimens. Second, 

 the less abrupt posterior flexure of the pectoro-humeral suture where it 

 leaves the free margin of the anterior lobe on each side. A large Oregon 

 specimen has the recurvature nearly as abrupt as in the Colorado and 

 Nebraska specimens, and Leidy figures one of the latter (Ancient Fauna 

 of Nebraska, PI. XX), where the recurvature is as in some of the Oregon 

 specimens. Thirdly, a convexity of the pygal and anal bones. This does 

 49 



