62 



AinoiiK iIh- soft-tinned tislics the most valuable as food for other kinds 

 is the f^izzardshad (Dorosoma).— this single fish being al)Out twice as common 

 in adults as all the minnow family +ak(;n together. It made forty percent. 

 of the food of the wall-eyed pike; a third that of the black bass: nearly 

 half that of the common pike or "pickerel": two-thirds that of the four 

 specimens of golden shad examined: and a third of the food of the gars. 

 The only other fishes in whose stomachsvit was recognized were the yellow 

 cat {Amiurus natalifi:) and the young white bass (Roccus). It thus seems to 

 be the especitil food of the large game fishes and other particularly pre- 

 daceous kinds. 



The minnow family (Cyprinida^i are in our waters especially appropri- 

 ated to the support of half-grown game fishes, and the smaller car- 

 nivorous species. They were found in the wall-eyed pike, the perch, the 

 black bass, the blue-cheeked sunfish. the croppie. the pirate perchi the 

 pike, the little pickerel', the chub minnow-', the yellow cat, the mud cat, 

 the dog-fish, and the gar. 



Suckers (Catostomatidse) I determined only from the pike, the 

 sheepshead, the blue-cheeked sunflsh, the yellow cat. and the dog-fish 

 (Amia). Buffalo^ and carp"* occurred in the pike, the dog-fish, and the 

 above sunfish. 



^rOLLrSK EATERS. 



The ponds and muddy streams of the Mississippi Valley are the native home 

 of mollusks in remarkable variety and number, and these form a feature of 

 the fauna of the region not less conspicuous and important than its char- 

 acteristic and leading groups of fishes. We might, therefore. reasonabl\" 

 expect to find these dominant groups connected liy the food relation: and 

 consistently with this expectation, we observe that the sheepshead. the cat- 

 fishes, the suckers, and the dog-fish And an important part of their food 

 in the molluscan forms abundant in the waters which they themselves 

 most frequent. The class as a whole makes aljout one-fourth of the food 

 of the dog-fish and the sheepshead.— taking the latter as they come, half- 

 grown and adults togetlier, about half that of the cylindrical suckers, — 

 rising to sixty per cent, in the red horse'. — and a considerable ratio (four- 

 teen to sixteen per cent.) of the food of the perch, the common catflshes 

 (Amiurus and Ictalurus), the small-mouthed suntishes. the top minnows, 

 and the shiner (Notemigonus). Notwithstanding the abundance of the 

 fresh water clams or river mussels (Unio and Anodonta). only a single 

 river fish is especially adapted to their destruction, viz.. the white perch 

 or sheepshead: and this species derives, on the whole, a larger ])art of its 

 food from univalve than from bivalve mollosks. the fornuM" being eaten 

 especially by half-grown specimens, and tlie latter being the chief depend- 

 ence of the adults. 



The ability of the catflshes to tear the less powerful clams from their shells 

 has been especially discussed in another paper* containing the details of 

 the food of the family. Even the very young Unios were rarely encount- 

 ered in the food of flshes, my notes recording their i^resence in only three 

 sunflshes, a brook silversides, and a perch. Large clams were eaten freely 

 by the full-grown sheepshead— whose enormous and powerful piiaryngeal 

 jaws with their solid pavement teeth are adapted to crushing the shells of 

 mollusks— ant! by the bull-heads (Amiurusi. especially the marbled cat-. 

 The small and thin-shelled SphaM-iums are much mon^ frequent objects in 

 the footl of moUusk-eating flshes than are the Unios. This genus alone 

 made twenty-nim> ])er cent, of the food of our one hvuidred and seven 

 specimens of the sucker family, and nineteen per cent, of that of a dozen 

 dog-flshes. Among th(> suckers it was eaten greedily by both the cylindri- 

 cal and the deep-bodied species, although somewhat more freely by the former. 

 Even the river carp=', with its weak pharyngeal jaws and delicate teeth, 



'Esox verinii'ulatus. -'Semotilus. •''Ictiobus. ^Carpiodes. 

 ♦Bull. 111. St. Lab. Nat. Hist.. Vol. II.. pp. 457. 458. 

 iMoxostoraa. '-.\niiurus niarmoratus. -'Carpiodrs. 



