A STUDY OF TWIX LAKES, COLOEADO. 175 



upon these small crustaceans. The great majorit_y of the adult females had either 

 eggs or developing embryos in their brood chambers. Whether the eggs are 

 destroyed during their passage through the alimentary canal or not is still an open 

 question. Fric and Vavra (1894) found that sunuuer eggs sometimes pass through 

 the canal undigested, but they did not determine whether these eggs had lost their 

 vital power. Steuer (1901), however, raised a Ceriudaphnla from an ephippium 

 which was taken from the intestine of a Ksh. But, even if the majority of the eggs 

 escaped digestion and developed afterwards, it hardly seems probable that the 

 embryos escaped also, and they alone represented a very large additional loss. 



Steuer (1901) calls attention to the likelihood of overestimating the value of 

 Entomostraca as a direct source of food for tishes. He thiidis that, in vei'y many 

 cases, they enter the digestive tract of the tish only indirectly; that is, after being 

 eaten by some animal which is in turn eaten by the fish. There was no room for 

 doubt as to their being eaten directly b}- the trout in these cases. In a number of 

 instances there was nothing else in the stomachs; and in stomachs which contained 

 additional fonrl the additional food in most instances consisted of insects that had 

 accidentally fallen into the water, and these of course had not l)een feeding on 

 Entomostraca. 



BIBLIOGRAPHY. 



Abbott, C. C. 1878. Notes on some fishes nf the Dehiware Kiver. Rejiort V . S. Fish Commission, 



1875-76 ( 1878) , p. 825-845. 

 Baird, Spencer F. 



1872. The food of the sea-herring. Annual Record of Science and Industry for 1S7], p. 208-210. 



1872. Food for youn^ trout. Ibid., 1871, p. 217. 



1872. Nutrition of young fish in hatching establisliiuents. Ibid., 1871, p. 350-352. 



1873. Food of shad. Ibid., 1872, p. 426. 



1874. Food of the basking shark. Ibid., 1873, p. 328-329. 1S74. 

 1874. Food for diminutive trout. Ibid., 1873, p. 447. 



1874. Increase in tlie growth of trout. Ibid., 1873, p. 448. 



1875. Food of the shad. Ibid., 1874, p. 310-311. 



1876. Food for trout. Ibid., 1875, p. 433-434. 



Baihd, W. 1857. Notes un the food of some fresh-water, fishes, more jiarticularly the vendace and 



trout. Edinburgh Pliilosopliical Journal, n. s. , vol. vi, 1857, p. 17-24. 

 Barfcrth, D. 1876. UeberNahrungundLebensweiseder Saline, Forellen,undMaitische. Inaugural 

 dissertation. 41 p. Translated by O. Jacobson, in Report U. S. Fish Commission, 1873-74 and 

 1874-75 (1876), p. 73.5-7.59. 

 Beardsley, A. E. 1902. Notes on Colorado Entomostraca. Transactions Amei'ii'an Microsccipical 



Society, vol. xxnr, ji. 41-4S. 1902. 

 BiRGE, E. A. 1897. Plankton studies on Lake Mendota (II). Transactions Wisconsin Academy of 

 Sciences, Arts, and Letters, vol. xi, 1897, p. 274-448, 28 pi. 

 1904. The theruiocline and its biological significance. Transactions American Microscopical 

 Society, vol. xxv, 1904, p. .5-33, 2 jil. 

 Brook, G. 



1886. Preliminary account of the food of the haddock. Fourtii Annual Report of Fisheiy Board 



for Scotland, app. F, no. 6, p. 128-134. 1886. 

 1886a. Preliminary report on the food of the cod. Fourth Amuial Report of Fisliery Board for 

 Scotland, app. F, no. 6, p. 134-147. 18"j. 



1887. Notes on the food of young Gadidae. Fifth Annual Report of Fishery Boanl for Scotland, 



app. F, no. 10, p. .326-327. 

 Brook, G., and Calderwood, W. L. 1886. Report on the food of the herring. Fourth Annual 

 Report of Fishery Board for Scotland, a|i[«. F, no. (i, p. 102-12S. ISSi!. 



