232 



BULLETIN OF THE BUREAU OF FISHERIES. 



The table shows six specimens with food in the alimentary canal, and we have 

 records of four others. Five of the lo fish whose stomach contents were studied con- 

 tained fish, in one case a sunfish, in the other cases the contents were not determinable. 

 Three contained the remains of insects, in one case a dragon fly larva. Two contained 

 each a crayfish; in one this was determined as Cambarus virilis, a species which is 

 common in the deeper water of the lake and which occurs also under logs and the like 

 in shallow water. In respect to food, the rock bass of Douglas Lake agree with those 

 of Walnut Lake and of Illinois waters. 



Systematic descriptions give the length for the species as 8 to lo inches, which 

 agrees very well with the 9 to 13 inches of our adult specimens. The weight-length 



7 s 9 



/O // /Z /3 /-* /S 



Fig. 4. — Graph showing the relation of length and weight in the 1 7 specimens of rock bass. Amhloplites Tuftestris, included 

 in table iv. Each space on the horizontal line represents one-half ounce; each space on the vertical hne oue-haU 

 inch. Curve drawn free-hand. 



curve is given in figure 4, but there are no similar data from other localities for com- 

 parison. There is nothing in our data to indicate that Douglas Lake is an unfavorable 

 habitat for this species. 



A rock bass i]4 inches long noted near the laboratory dock paid no attention to a 

 baited hook until touched by it, but was then hooked. It proved to be blind, emaciated, 

 with characteristically large head and without mesenterial fat. It was not too large for 

 a good sized pike to swallow, and it is remarkable that it should have escaped death so 

 long. The struggle for existence among the inhabitants of the lake had not been severe 

 enough to eliminate either the blind rock bass or the crippled pike already referred to. 

 Both were finally eliminated by man. 



Lepomis pallidus QAitchiW), bluegill. — Records for 8 specimens are given in table v. 



