770 THE WHITE EIVEE FAUNA. 



not appear in a very large and a very small specimen. It may be charac- 

 teristic of the male sex. 



One of the Oregon specimens is much larger than the others, and has 

 the anterior lobe a little more produced, in this respect resembling the largest 

 Colorado specimen. I add the measurements of these two specimens: 



Measurements. 



No. 1. — Colorado. 



It. 



Length of plastron 390 



Widtli of plastron at middle '. 310 



Width of anterior lobe at base 200 



Length of anterior lobe 145 



Elevation of carapace 210 



No. 2. — Oregon. 



Length of plastron 420 



Width of plastron at middle 345 



Width of anterior lobe at base 215 



Length of anterior lobe 157 



Elevation of carapace 1*0 



The Oregon form has been regarded by Leidy as a distinct species, 

 with the name Stylemys oregonensis* He adduces the thinness of the verte- 

 bral bones as its distinctive character. For the present I cannot admit it 

 as more than a variety, although the skull and feet must be known before 

 its position can be finally decided. 



LACEEIILIA. 



Several species of this order were discovered by myself in the White 

 River beds of Coloi'ado in 1873, and a single species was found by one of 

 my parties in the John Day beds of Oregon. With the exception of the Pelto- 

 saurus granulosus they rest upon fragmentary remains, which are in some 

 instances not sufficient to furnish evidence of the position of the species in 

 the system. The genera which are determinable display affinity to types 

 now existing in the warmer parts of North America. 



•Report U. S. Geol. Surv. Terrs., I, p. 225. 



