of development they would hardly swim into such a 

 place from the open lake. This is a bottom form as 

 was shown by the fact that it was far more abundant in 

 the Helgoland trawl than in either of the meter nets. 

 In the latter, also, it was more abundant near the bot- 

 tom than at the surface except at 1 or 2 stations near 

 the western end of the lake. At the eastern end of the 

 lake during 1928 it showed a decided preponderance 

 on the American shore. At 2 of the littoral stations 

 off the New York shore the Helgoland trawl brought up 

 a large plankton catch that was practically 100 percent 

 Leptodora . This indicates that Leptodora has the habit 

 of swarming or gathering in large numbers in a single 

 limited area like the marine copepod Calanus fin- 

 marchicus. Since this swarming takes place in the 

 shallow water of the marginal and littoral zones of the 

 lake it brings Leptodora into the very region frequented 

 by young fish, where they can be of most service as 

 food. Eaten by Cisco and lake herring. 



65. Leydigia ac anthocercoides (Fischer). Found 

 at 5 marginal stations, 4 of which were on the Can- 

 adian shore; abundant only at Turkey Point, 



66. Leydigia quadrangularis (Leydig). Found at 

 6 of the marginal stations, 4 on the American shore; 

 very limited in numbers everywhere. Eaten by bull- 

 head and carp. 



67. Macrothrix laticornis (Jurine). Found at only 

 2 marginal stations on the Canadian shore at the east- 

 ern end of the lake. Eaten by carp sucker and redhorse 

 sucker. 



68. Macrothrix rosea (Jurine) Found only at Cres- 

 cent Beach and in the ponds on Point Pelee. Eaten by 

 the carp and carp sucker. 



69. Moina affini s Birge. Found in very small 

 numbers in the ponds on Point Pelee; also reported by 

 Bigelow (1922). Eaten by carp. 



70. Moina rectirostris (Leydig). Found only in a 

 mud washing at Tonawanda on the American shore of 

 the Niagara River and in the old Erie Canal. It is eaten 

 by carp and the carp sucker. 



71. Monospilus dispar Sars. Found at 3 marginal 

 stations on the Canadian shore, but nowhere abundant. 

 Eaten by yeUow perch. 



72. Oxyurella tenuicaudis (Sars). Found only 

 in a pond of the Cayuga Creek drainage in very small 

 numbers. Eaten by the yellow perch. 



73. Pleuroxus aduncus (Jurine). A few speci- 

 mens were found at Cedar Bay on the Canadian shore 

 and in a small pond of the Cattaraugus Creek drain- 

 age on the American shore. Eaten by the carp and 

 the carp sucker. 



74. Pleuroxus denticulatus Birge. Found at 3 

 marginal stations on the Canadian shore and 6 on the 

 American shore, abundant at 1 station on either side. 

 Eaten by an unidentified minnow. 



75. Pleuroxus procurvatus Birge. A few speci- 

 mens were found in the ponds on Point Pelee; pre- 

 viously reported by Bigelow (1922). Eaten by yellow 

 perch. 



76. Pleuroxus striatus Schoedler. Found at 2 

 marginal stations on the Canadian shore and 2 on the 

 American shore; not abundant. Eaten by the carp 

 sucker. 



77. Pleuroxus trigonellus (O. F. MflUer). A few 

 specimens were found in the ponds on Point Pelee; 

 previously reported by Bigelow (1922). Not found in 

 the food of any lake fish. 



78. Polyphemus pediculus (Linnaeus). Reported I 

 by Bigelow (1922) from the ponds on Point Pelee but 



not collected during the present survey. Not in the 

 food of any lake fish. 



79. Scapholeberls aurita (Fischer). Found at 2 

 marginal stations on the Canadian shore and 2 on the 

 American shore; not abundant. Eaten by carp. 



80. Scapholeberls mucronata (O. F. MUller). 

 Found at 14 marginal stations evenly divided between 

 the two shores and abundant at 2 stations on either 

 side. Eaten by the carp and carp sucker. 



81. Sida crystallina (O. F. MUller). Found at 

 nearly every marginal station and in the littoral and 

 lacustric zones, frequently very abundant. The sur- 

 face net captured far greater numbers than the bot- 

 tom net through June, July, and August, but in Sep- 

 tember the numbers were about equally divided be- 

 tween the two nets. It attained its highest percentages 



170 



