442 Illinois Stale Laboratory of Natural History. 



Two large examples taken from the Illinois at Havana in 

 October, 1887, were found to have eaten similar food. In one, 

 sixty per cent, consisted of small univalve Mollusca (Valvata 

 carinata and Amnicola), the remainder being almost wholly 

 insects chiefly larvae of water beetles (Hydrophilidae) and 

 larval Ephemeridae (largely Cgenis). About five per cent, of 

 Lemna occurred in this fish, probably taken by accident, as 

 the river was covered with a film of duckweed at the time. A 

 few Chironomus larvae and an Allorchestes were also noted. 

 In the other specimen only five per cent, of the food consisted 

 of mollusks (the same species as before, together with a small. 

 Sphaerium). Larval Hydrophilidae made eighty per cent, of the 

 contents of the intestine, and Ephemeridae (Caenis) more than 

 ten per cent. Chironomus and other dipterous larvae, Pluma- 

 tella, and a little Wolffia, were likewise recorded. 



In a third example, only five and a half inches long, the 

 locality of which is not known, the food was chiefly Plumatella, 

 the only other elements being small case-flies (Phryganeidae), a 

 minute univalve shell (Strepomatidae), and a few small Chiron- 

 omus larvae. 



MOXOSTOMA MACROLEPIDOTUM, LeS. COMMON RED HORSE ; 

 WHITE SUCKER. 



The genus Moxostoma, the commonest and most typical of 

 the cylindrical suckers, is represented in Illinois by three 

 species, two of which, aureolum and macrolepidotum, occur 

 everywhere in lakes, rivers, and smaller streams. We have 

 encountered M. carpio but rarely, and my studies relate only to 

 the two former species. 



In macrolepidotum the gill-rakers of the anterior row are 

 twenty-five to twenty-seven in number, the upper twenty to 

 twenty-two being elongate, triangular, stout, and crenate within, 

 about three fourths as long as the filaments of the gill; 

 while the lower five or six of this series, all of the second 

 series of the anterior arch, and all of the other rakers of the 

 gills, including the row upon the pharyngeals, have the form 

 of transverse leaf-like plates with crenate edges, projecting in 

 triangular outline a little beyond the margin of the thick gill 

 arch. The gills seem but slightly separable, and the branchial 

 apparatus is coarse and ineffective. 



