CRUSTACEA AS FOOD FOR YOUNG FISH, 11 



ducecl 6 eggs, was 5.8 mm. long. The average number of eggs pro- 

 duced by a female was 22, repeated at average intervals of 11 days. 

 The breeding season of the species was from April 18 to November 

 3, a total of 199 days, when the temperature ranged from a minimum 

 of 11.1° C. (51.98° F.) to a maximum of 30° C. (86° F.). It was 

 calculated that the productive capacity of one pair and its progeny 

 was 24.221. The young remained in the brood pouch an average of 

 2.25 days. The period from oviposition to hatching was 8 days at 

 an average mean temperature of 23° C. (73.4° F.) and in 180 days 

 from hatching the young grew from 1.53 mm. to 9.32 mm. in length. 



Gammanis limnceus. — This is the "Caledonia shrimp" of early 

 fish-cultural fame. Its general distribution is comparatively wide, 

 occurring in certain characters of water. U. S. National Museum 

 records (1907) are: Aroostook County, Me.; Caledonia, N. Y. ; Mar- 

 quette and Ann Arbor, Mich.; Isle Eoyal, Lake Superior; Fort 

 Wingate, N. Mex. ; Wasatch Mountains; Shoshone Falls, Idaho; 

 Salt Lake City, Utah ; Flathead Lake, Mont. ; Yellowstone National 

 Park. 



Embody (1911) says it seems to occur in greatest numbers near 

 headwaters of a brook and in its tributaries, and even in springs 

 themselves. In the upper part of the brook the yearly range of 

 temj^erature was from 6° to 12° C. (42.8° to 53.6° :F.). The largest 

 numbers of individuals were found associated with the roots of the 

 water cress, thick tangles of Chara, and under decaying leaves. No 

 individuals were found well down the brook where the water gave a 

 temperature above 16° C. (60.8° F.) They were equally abundant in 

 rapid and quiet water, in any place where there was sufficient ac- 

 cumulation of Chara, water cresses, and dead leaves, and where the 

 water was sufficiently cool. 



This species, according to Embody (1911), attains the largest size 

 of the four species observed. The largest individual seen was 22.42 

 mm. (about 0.88 inch) long. The average size of 13 egg-producing 

 females was 13.36 plus mm. (about 0.52 inch), and the smallest of 

 these, which was 93 days old and yielded 8 eggs, was 9 mm. (about 

 0.35 inch) long. The average number of eggs produced by a female 

 was 25, repeated seven times in the breeding season of 266 days, 

 from January 8, 1909, to September 10, 1910. At this time the 

 temperature ranged from 6° to 12° C. (42.8° to 53.6° F.), with aver- 

 age of 9° C. (48.2° F.) in 26 readings. The total reproductive 

 capacity of one pair and its progeny during this season was calculated 

 as 1,619. Observations upon two individuals gave the period from 

 oviposition to the date of hatching as 18 and 21 days, the average 

 mean daily temperature being 16.9° and 14.8° C. (62.42° and 58.64° 

 F.), respectively, in February. The young remained in the brood 

 pouch on an average of 3 days. In 180 days from hatching the 

 young grew from 2.16 mm. to 11.73 mm. (about 0.085 to 0.46 inch) 

 in length. 



Riialella Icnic'h'er'hockeri. — This form is one of the commonest 

 fresh- water amphipocls in the Eastern States. It has a very 

 wide distribution, and in this country is found from Maine to 

 Florida and California. The U. S. National Museum records (1907) 

 are: Caribou, Me. ; Cambridge and Quisset Pond, Mass. ; Ann x\rbor, 

 Mich.; Isle Koyal, Lake Superior, Wisconsin River, Lake Geneva, 



