TESTUDO. 105 



specimen upon the sixth and seventh marginal plates, but in the smallest upon the 

 seventh only, between the abdominal and seventh marginal scutes. 



MEASUREMENTS. 



THREE SPECIMEKS. 



Smallest. Medium. Largest. 

 Estimated length of sternum ........ 7 in. 



Breadtli of sternum at inferior border of marginal scutes . . . 4f in. 41 in. 5i in. 



Length of transverse curve of the carapace from the level of the sternum 8| in. 



Height from the level of the sternum . . . . . . . 3 in. 



Length of the lateral marginal plates . . . . . . . IJ in. If in. 



Height of latter from the level of the sternum . . . . . IJ in. 



Testudo hemispherica, Leidy. 



(Plates XX., XXIV. Fig. 3.) 



Emys JiemispTierica, Leidy: Proc. Acad. Nat. Sci., 1851, v., 173. 



Testudo Jiemispherica, Leidy : Proc. Acad. Nat. Sci., 1852, vi., 59 ; Owen's Rep. of a Geol. Surv. of Wise, etc., 

 670. 



This species originally was established upon a specimen consisting of the sternum 

 with a small portion of the carapace attached, from the collection of Capt. Van Vliet. 



In Dr. Owen's collection, a nearly entire carapace and sternum of the same species 

 are preserved. 



The carapace is relatively more convex and hemispheroid, or rather hemi-ovoid, 

 than that of any of the other fossil turtles brought from Nebraska. 



The lateral marginal plates are vertical; the axillary notches are directed out- 

 ward and downward ; the inguinal notches present downward ; and the sternum is 

 quite flat, except that its anterior extremity inclines upward. 



In both specimens, the costal plates of the carapace had yet been unconnected by 

 suture with the adjoining marginal plates. 



The species presents the ordinary or normal number and arrangement of verte- 

 bral plates. 



Plates of the Carapace.— (PI. XX. 1.) The first vertebral plate is one and' a 

 quarter inch long by three-fourths of an inch broad; the succeeding plates, to the 

 eighth inclusive, are hexahedral; those to the sixth being nearly equal in size; and 

 the tenth transversely rhomboidal plate is three-fourths of an inch long by one and 

 a quarter broad. 



The first costal plate is three inches long by one and three-quarters broad, and 

 articulates with the first and second and four-fifths of the third marginal plates. 



The nuchal plate comes in contact with the position of the first costal scute at 

 the anterior angle of this, and here measures two and a half inches in breadth. 



The pygal plate is vertical, and measures one and a half inch broad. 



Plates of the Plastron.— (PI. XX. 2.) The sternum is truncated anteriorly, and 

 at its posterior extremity is rounded and emai'ginate. 



The entosternal plate is broad, pyriform, and extends for half an inch upon the 

 position of the gular scutes, reaches posteriorly the boundary of the humeral scutes, 

 and is about two inches long and broad. 



