270 BULLETIN OP THE BUREAU OF FISHERIES. 



Station 16; June 30; number examined, 10. Length: Maximum, 173; miuimum, 139; average, 

 149.6. Food: Chironomus sp. larvae, 7; Pelocaris feraoratus larvje, 2; Stratiomyia sp. larvse, i; Enal- 

 lagma antennatum nymphs, 4.1; Enallagma hageni nymphs, 5.5; Atax tiu'gidus nymphs, 1.5; Corixa 

 sp. nymphs, 30.6; Limnesia, 0.7; Hyalella, 5; Cyclops, 0.2; Eiuycercus, 17; Physa, 5; snails, 16.2; plant 

 remains, 4.9; debris, 0.5. 



Summary. — Food: Insect larvae, 51.7; mite, 0.7; amphipods, 5.; entomostracans, 17.2; MoUusca, 

 21.2; plants, 4.9; debris, 0.5. 



Station 17; July 7; number examined, 10. Length: Maximum, ^y, minimum, 25; average, 29.6. 

 Food: Chironomus fulviventris larvae, 1.6; Tanypus decoloratus larvae, 6.g; Plea minutissima larvae, 

 o.i; Corixa sp. nymphs, 1.5; Chironomid adult, o.i; Hyalella, 15.3; ostracods, o.i; Cyclops viridis, 2,9; 

 Cyclops, 40.4; Nauplii, 2.7; Daphnia, 0.1; Chydorus sphsericus, 8.9; Eurycercus, 11. 8; Acroperus, 0.2; 

 Ceriodaphnia, 0.1; Pleuroxus procvirvatus, 0.5; Bosmina, 6.5. 



Summary. — Food: Insect larvae, lo.i; adult insects, 0.1; amphipods, 15.3; Entomostraca, 74.2. 



Station 17; July 19; number examined, 9. Length: Maximum, 38.5; minimum, 34; average, 36.8. 

 Food: Chironomus fulviventris larvae, 9.1; Chironomus sp. larvae, i.i, Procladius sp. larvae, 0.9; Cri- 

 cotopus trifasciatus larvae, 3.7; May-fly nymphs, 5.5; Hyalella, 55.4; ostracods, 2.5; Cyclops, 0.2; Chy- 

 dorus sphaericus, 0.7; Eurycercus, 17.2; Ceriodaphnia, 4.6; Pleiu-oxus procvirvatus, 0.3. 



Summary. — Food: Insect larvae, 20.3; amphipods, 55.4; Entomostraca, 25.5. 



Station 18; August 7; number examined, 10. Length: Maximum, 54.5; minimum, 45.6; average, 

 50.4. Food: Chironomus fulviventris larvs, 16.2; May -fly nymphs, 24.9; Enallagma antennatum 

 nymphs, 4.5; Corixa sp. adult, 0.3; Hyalella, 39,6; ostracods, 0.8; Cyclops, 0.4; Daphnia, 0.5; Cerio- 

 daphnia, 13.9; filamentous algffi, 0.9; plant remains, 0.2. 



Summary. — Food: Insect larvae, 45.6; adult insects, 0.3; amphipods, 39.6; Entomostraca, 15.6; 

 algae, 0.9; plants, 0.2. 



Station 18; September 13; number examined, 2. Length: Maximum, 185; minimum, 182, aver- 

 age, 183.5. Food: Minnow remains, 50; Daphnia, 50. 



Grand summary for igi4, IQIS, and igi6. — Number examined, 115. Length: Maximum, 280; mini- 

 mum, 25; average, 99.9. Food: Tadpoles, 0.3; fish eggs, 3; insect larvje, 34.7; insect pupae, 1.7; adult 

 insects, 1.8; mites, 0.1; amphipods, 24.5; Entomostraca, 25.8; molluscs, 3.8; oligochaetes, 0.4; pro- 

 tozoans, + ; plant remains, 0.8; algae, 0.7; silt and debris, i.i. 



The perch apparently feeds mostly on insects (38.2 per cent), amphipods (24.5 per cent), and ento- 

 mostracans (25.8 per cent). Even large adults often have nothing in the alimentary canal except a great 

 number of cladocerans. Forbes and Richardson (1908) stated that the perch is wholly carnivorous. Its 

 food in rivers consisted of fish, molluscs, insect larvae, amphipods, shrimps, isopods, and crayfishes, and 

 of fish and crayfish in lakes. Hankinson (1908) found midges in all stages of development, crayfish, 

 insects and larvx, snails, leeches, and entomostracans. Tracy (1910) reports small fishes, insects, etc. 

 Reighard (191 5) found the perch in Douglas Lake eating each other. 



All these observations show that the perch is a versatile feeder. At any age it may feed largely on 

 entomostracans, insects, molluscs, or almost anything else that is edible. 



Percina caprodes (Rafinesque) var zebra Agassiz, log-perch. 



Data for I ()i 4 (Pearst, 1915, Boeleichthys fusiformis) . — Station 24; October 3; number examined, 7. 

 Average length, 65.6. Food: Insect larvae, 84; adult insects, 6.7; amphipods, 2.4; ostracods, 0.1; cope- 

 pods, 0.3; cladocerans, -|-; silt and debris, 6. 



Station 23, in rapids; April 28, 1915; number examined, 14. Length: Maximum, 94; minimum, 

 60; average, 76.3. Food: Fish eggs, 51.6; Chironomus larvae, 5.3; Hydropsyche altemans larvae, 10.3; 

 Hyalella, 14.2; Cyclops, 0.2; leech, 1.8; plant remains, 4.8; filamentous algae, 3.4; silt and dfebris, 7.8. 



Station 24; July 2; number examined, 2. Lengths: 79, 63. Food: Chironomus viridis larvae, 5; 

 C. lobiferus larvae, 5; C. tentans larva:, 7.5; Protenthes culiciformis larvs, 4;' Cricotopus trifasciatus 

 larvae, 27.5; May-fly nymphs, 3.5; Ecdyurus maculipennis nymphs, 1.5; Callibaetis nymphs, i; Crico- 

 topus trifasciatus pupa, 15; Chironomus lobiferus pupae, 10; C. tentans pups, 5; leech, 15. 



Summary. — Food: Insect larvae, 53; pupae, 30; leech, 15. 



Station 23, on beach at mouth of river; August 19; number examined, i. Length: 44. Food: 

 Chironomus viridis larvae, 25; C. flavicingula larvae, 15; C. tentans larvae, 50; C. tentans pupae, 6; cladoc- 

 erans, 4. 



