188 



Amia (Peotamia) media. • 



Figs. 7 to 9 represent a vertebral centrum, obtained at the junction of the 

 Sandy and Grreen Rivers, during Professor Hayden's expedition of 1870. In 

 its form and proportions it resemJiles a centrum from near the fore part of 

 the dorsal series of Amia calva, but pertainetl to a species double the size. 

 It presents several peculiarities which render it probable that it belongs to a 

 related genus. The sides of the centrum ai-e less contracted than in Amia, 

 and the pair of ridges beneath are substituted by a pair of oval pits. The 

 parapophyses project transversely just above the middle, and are very short. 



The measurements of the specimen are as follows: 



Lines. 



Leugtb of ceutrum inferiorly 5. 5 



Height of centrum 10. 2 



Breadth of centrum 1.3. 



Figs. 10, 11 represent a vertebral centrum, found by Dr. Carter on Dry 

 Creek. It resembles a centrum of Amia calva from the back of the dorsal 

 series, but is double the size. It presents beneath a pair of grooved ridges, 

 as in A. calva. 



The specimen measures as follows : 



Lines. 



Length of centrum inferioi'ly 4. 



Height of centrum 7. G 



Breadth of centrum 8. 6 



Amia (Protamia) gracilis. 



Figs. 23, 24, Plate XXXII, represent a vertebral centrum found by Dr. 

 Cai'ter, together with a number of ganoid scales, opposite the second cross- 

 ing of Henry's Fork of Green River. The centrum has a different color from 

 the scales, and clearly did not belong to the same fish. It is from near the 

 middle of the dorsal series, and pertained to a smaller species than Amia 

 calva The two ridges beneath the centra of the latter are substituted by 

 ^two oblong fossae. 



The measurements of the specimen are as follows: 



Lines. 



Length of vertebral centrum inferiorly 1. 8 



Height of vertebral centrum 3. -t 



Breadth of vertebral centrum 3. 8 



