FISHES, LAHONTAN SYSTEM OF NEVADA AND NORTHEASTERN CALIFORNIA. 8 1 



In the preserved specimen the dorsal surface including the upper third of body is jet black, no spots 

 being visible; sides silvery, with greenish and yellowish reflections; ventral surface white; dorsal fin 

 with about lo rows of very small, elongate, black spots. Adipose fin with 4 round spots. Caudal with 

 small, elliptical spots arranged along the rays. In life the upper surface including the head and snout 

 was deep emerald green , yellowish reflections appearing in some lights, and scattered dark spots occurring 

 here and there from the occiput to the tail; sides silvery, the metallic color extending almost to the tip 

 of caudal fin; lower surface dead white. There is no red or pink on any part of the body or fins. 



The following proportional measxirements are recorded in hundredths of the length to base of caudal : 

 Length head 0.225; depth body 0.2; depth caudal pedimcle 0.095; length caudal peduncle 0.18; length 

 snout 0.065; length maxillary 0.115; diameter eye 0.04; interorbital width 0.075; depth head 0.15; 

 snout to occiput 0.14; snout to dorsal 0.475; to ventral 0.505; length base of dorsal 0.12; of anal o.i; 

 height dorsal 0.125; height anal 0.12; length pectoral 0.15; length ventral 0.125; length caudal 0.21. 



The specimen here described was caught by the writer shortly after sundown, while trolling with 

 rather heavy tackle at a depth of about 40 feet below the surface. On being brought near the boat the 

 fish left the water twice in spite of its heavy impediments, in strong contrast to the behavior of the more 

 sluggish cutthroat, which even with light tackle may sometimes be brought to gaff without breaking the 

 surface. The immediate region of its capture and the water near by were carefully worked over for a 

 considerable time without success. That it was taken with a spinner demonstrates that it feeds, at 

 least at times, on minnows. The stomach contained parts of a small minnow together with the remains 



Fig. 9. — Salmo smaragdus. Type. Emerald trout. 



of insects (beetles and bugs); but whether the latter had been taken directly or as part of the captured 

 fish could not be determined. 



Little is known of the habits of this species. It is said to be more frequently taken in the northern 

 parts of the lakes, far from the inlets. It is not known to enter the river, and consequently it is sup- 

 posed to spawn in the lake. 



It will be noted that both this and the preceding species are indigenous to the same basin. None 

 the less they may be regarded as particularly good examples of species which differentiated through 

 the agencies accompanying isolation. For although Lake Tahoe, the habitat of S. regalis, and Pyramid 

 Lake are connected by the Truckee River, which has its origin in the former and flows into the latter, 

 they are in effect separated by what to some species is an impassable barrier rather than an open 

 channel, the turbulent waters of the river plunging down 2,300 feet over a bowlder-strewn bed but 

 little more than a himdred miles in length. Along with isolation the species are subjected to very 

 different environmental conditions. The water of Lake Tahoe comes almost immediately from melt- 

 ing snow and is imusually ptu-e and fresh, while that of the lower lake into which it finally flows is so 

 charged with various salts that no arborescent vegetation grows on the shores. 



Cottus beldingl Eigenmann. Desert riffiefish. 



Coitus beldingi is closely related to C. gulosus, C. punctulatus, and the doubtful form C. klamaihen- 

 sis, differing from the first and last in having fewer rays In the anal fin and from C. punctulatus in the 

 weaker armature of the preopercle. Like the latter, C. beldingi has a smooth skin and usually a narrow 

 band of palatine teeth. The four forms here enumerated resemble each other very closely and their 



