The Food of the Smaller Fresh - Water Fishes. 75 



mcatary canal, in the funuLT the teeth are usually sharp-edged or 

 hot)ked, in the latter truncate, hanuner, or spoon-shaped." 



"In the American genera, as far as included in the scope of 

 this essay, the peculiarities of the intestines correspond with the 

 food. In the Albarnellas ruhrifwns.,^ tl'<^y f*^'"*' but four-fifths the 

 length of head and body (excluding caudal fin). In Hi/psile- 

 pis kentHJiiensis^^ P/totogenis leucoj^s, Aryi/reus atro7iasi(s^ and 

 irasutxs.,'' Ericymba buccata, and Exoglossum maxilUngua^ about 

 seven-ninths; the food of the last five species is insects and crus- 

 taceans, the last depending largely on mollusca. In the species 

 of Ceratichthys, Semotilus, and Hybopsis, with Hypsilepis cor- 

 nutiis,* fifteen-sixteenths to eqvial the length; the habits insectiv- 

 orous. The genera with longer intestines are, first, Stilbe^ one and 

 two-fifths to one and three-fourths the length; Chrosomus, Hybor- 

 hynchus, and Pimephales two and two-fifths to two and two-thirds, 

 and Hy1)ognathus four times. The intestines in these are gener- 

 ally filled with a soft, dark-colored slime, without remains of 

 insects, but of vegetable origin. In the remarkable genus 

 Campostonia the canal extends to between eight and nine times 

 the length, and, like that of other vegetable feeders, is usually 

 found occvipied by the ingesta for a considerable part of its 

 length." 



This statement is in the main correct as far as it goes, but it 

 will be seen from the following data, and from the discussion of 

 the food of the family, that it is far from the truth with respect to 

 the germs Campostoma and its allies. 



If we examine the alimentary structures of the Cyprinida^, to 

 which reference has been made in describing the food of the pre- 

 ceding families, we shall find these fishes easily divided into at 

 least four tolerably distinct groups, defined by characters drawn 

 from the gill-rakers, the pharyngeal teeth and the intestines. In 

 all but two of the genera of this paper* the gill-rakers are short 

 and insignificant. The pharyngeal teeth may be either hooked or 

 plain, and with or without grinding surface, while the intestine 

 varies in length from less than that of the body without the head 



'Minnilu.s or Notropis. "Photoyenis analostanus. ^Rhiniclithy.s. ^Lux- 

 ilus cornutus. ^Notemigonus. 



■■I have used here, for convenience' sake, tlie nouienclatun! of the 

 Catalogue of the Fishes of Illinois, publislied in our third bulletin. 



