ABT. 18, CATOSTOMIDS OF THE BONNEVILLE SYSTEM SNYDER. 6 



peduncle more attenuate, 0.15 to 0.18; the eye larger, 0.03 to 0.35; 

 and the fins, excepting the caudal considerably longer. The dorsal 

 rays number 11, occasionally 12. 



Proportional measurements of 10 specimens of Pantosteus virescens from Weber River 



near The Devil's Slide. 



Length of body (inillmieters)..|320 



Length of head 1 0. 



Depth of body 



Depth of caudal peduncle 



Length of caudal peduncle 



Length of snout 



Diameter of eye 



Interorbital width 



Depth of head 



Snout to occiput 



Snout to dorsal 



Snout to yentral 



Length base of dorsal 



Length base of anal 



Height of dorsal 



Height of anal 



Length of pectoral 



Length of yentral 



Length of caudal 



Dorsal rays 



Anal rays 



Scales lateral series 



Scales above lateral line 



Scales below lateral line 



Scales before dorsal 



297 

 0.20 

 .17 

 .08 

 .135 

 .115 

 .025 

 .086 

 .135 

 .175 

 .48 

 .58 

 .135 

 .075 

 .16 

 .17 

 .175 

 .148 

 .212 



11 

 7 



93 



22 



15 



57 



In this species the mountain suckers appear to reach their largest 

 size, and they are to be found at their best in Weber River, where 

 schools numbering thousands of individuals may at times be seen. 

 They occur in the more mountainous parts of the basin, thriving 

 well where the channel is broad and the water deep. They were 

 encountered in numbers at Wanship, and again at several points 

 between Wanship and the mouth of Echo Creek. Farther down the 

 river, particularly in the vicinity of The Devil's Slide, they were met 

 (July 26) in schools of large size. At a distance of 15 or 20 miles 

 below the latter place, none was seen. 



The schools move slowly up or down stream, winding about over 

 the river bed in true sucker fashion. When feeding, small detach- 

 ments occasionally separate from the main school, and moving along 

 slowly and cautiously, the different individuals lazily roll about on 

 the bottom, scraping food from the surface of the rocks. They are, 

 however, very nervous and cautious fishes, fleeing at the approach of 

 a shadow, or the jar of the gravel crunched beneath the observer's 

 feet. Panic seizes an individual suddenly parted from a school 

 although groups of widely separated and perfectly quiet fishes may 

 at times be seen. 



In Weber River they appear to greatly outnumber the other large 

 fishes, Catostomus ardens associates with this species, and its indi- 

 viduals may be recognized by their more robust, greenish and bronzy 

 bodies, and pink fins. One haul of the collecting seine took 758 fish 



