FISHES, LAHONTAN SYSTEM OF NEVADA AND NORTHEASTERN CALIFORNIA. 69 



Measurements of Agosia robusta. 



Length of body mm 



Length head 



Depth body 



Depth caudal peduncle 



Length caudal peduncle 



Length snout 



Diameter eye 



Interorbital width 



Depth head 



Snout to occiput 



Snout to dorsal 



Snout to ventral 



Length base of dorsal 



Length base of anal 



Height dorsal 



Height anal 



Length pectoral 



Length ventral 



I^gth caudal 



Dorsal rays 



Anal rays 



Scales lateral line 



Scales above lateral Une 



Scales below lateral line 



Barbels 



Fallen Leaf Creek, near Tallac, Lake 



Tahoe. 



58 



S& 



S6 



Susan Creek. 10 miles below Susanville. 



58 



0.34 



■25 



.IIS 



.36 



.08 



.06 



.07 



•17 



• 31 



.56 



.50 



.11 



. 10 



■19 



■15 

 .36 



•IIS 

 .36 



. 10 

 •OSS 



.07 

 •17 



■ 31 



•53 

 •47 

 •"5 

 . 10 

 . 20 

 .18 

 •33 

 •17 



•3S 



8 

 7 

 76 

 13 

 9 



o. 24 

 ■25 

 • los 

 .34 

 .08 

 .06 

 •07S 

 ■17 

 . 21 

 ■55 

 ■ SO 

 . 12 

 ■<>9S 

 ■19 

 .16 

 .19 

 •IS 

 .34 



9 



7 

 73 

 13 



9 



•25 

 .08 

 .06 

 • 06s 

 .16 



•54 

 .48 



.16 



•25 



o. 36 



.36 



. 10 



.26 

 .08 

 • 045 

 .06 

 .16 



.20 

 •54 

 ■51 

 . II 

 . 10 

 .16 

 .16 

 •17 

 •13 

 •235 



0.26 

 •25 



. 12 



. 21 



.08s 



.06 



•07 



.18 



. 22 



•58 



•53 



. II 



.09 



•17 



•17 



.18 



•IS 



•24 



• OS 



.08 



.i5 



. 20 



•55 



•51 



. 10 



.08s 



.18 



.16 



•17 



■15 



25 



225 



13 



24 



08 



°5S 



°7 



17 



20 



56 



St 



13 

 08 

 16 

 16 

 17 



8 



7 



65 



14 



Coregonus williamsoni Girard. Mountain whitefish. 



Sufficient material for a careful comparison of whitefish from the Lahontan and Columbia systems 

 is not at hand. They seem to be alike, but the appearance of differences when series of each are com- 

 pared would not be regarded with surprise. 



The species is found in the Truckee, Walker, and Carson Basins, it was reported from the Humboldt, 

 but no evidence of its occiurence elsewhere in the system was found. It spawns in October, large 

 numbers then moving up the tributaries of Lake Tahoe. The migration is said to last about two weeks, 

 being at its height near the middle of the month. Males collected at that time had tubercles on the. 

 posterior part of the body and tail, both above and below the lateral line. 



An example from Carson River, near Genoa, was silvery in life, tinted with pale olive above, white 

 beneath. This specimen measured 395 millimeters. A smaller one, 185 millimeters long, was silvery, 

 somewhat darker above than below. When the body was turned , indistinct parr marks appeared in some 

 lights on the sides, which became more evident after preservation. Examples from 150 to 230 milli- 

 meters long, taken at Lake Tahoe, show no parr marks, while others measuring 95 to 145 millimeters, 

 collected in Fallen Leaf Creek, are broadly marked along the sides. These usually have nine almost 

 square, round, or somewhat oval dark spots on the sides, each of which is about four scales wide, their 

 edges extending just below the lateral line. The first is immediately behind the gill opening; the last 

 at the base of the caudal fin. Those near the middle of the body are largest. Occasionally a spot is 

 very small or absent, or a supernumerary may appear anywhere along the median line. Above this 

 row are many smaller spots, close together and without any definite arrangement. With growth the 

 smaller spots are first to disappear. 



The mountain whitefish seems to be particularly fond of the eggs of spawning fishes, and sometimes 

 their stomachs will be found filled with the eggs of their own species. It rises to the fly at times, is as 

 game as a trout, and by some is preferred as a food fish. 



A further comparison of specimens of this species with those of C. oregonus Jordan and Snyder, 

 from the Willamette River, fully warrants the recognition of the latter. 



