Article VIII. — On the Food Relations of 

 a Summary and Discussion. — By S 



The principal object of the research reported in the series 

 of papers* of which this is the concluding number, is to 

 determine more precisely than has hitherto been done the rela- 

 tions to nature of the various genera and families of the fishes 

 of an interior region. This purpose has led especially to a study 

 of the food relations of the groups, for through these, chiefly, 

 fishes exert their influence on the outer world, and are them- 

 selves impressed in turn ; and thus have appeared a number of 

 subordinate considerations having a bearing, more or less 

 direct, on the main intention of the study. 



An examination of the special relations of their food and 

 feeding structures gives us clues, not only to the present 

 significance of fishes, but also to their past effect on life at 

 large, showing how they must have modified the course of 

 evolution; and the occasional occurrence in a fish of food pre- 

 hensile structures out of present relation to its feeding habits, 

 may throw light on the history of its group, indicating condi- 

 tions of existence once normal to it but now outgrown. 

 Evidence of similar application may also be obtained by a 

 comparison of the food of the young and of the adult. 



The feeding apparatus exhibits some of the most significant 

 examples of correlation of structure, important to an acquaint- 

 ance with the course of development in fishes, but not compre- 

 hensible without a knowledge of the food for whose appropria- 



* Published at intervals from 1877 to 1888, in the first and second 

 volumes of the Bulletin of this Laboratory, an follows: "The Food 

 of Illinois Fishes" (Vol.1.. No. 2, pp. 71-89), "The Food of Fishes " 

 (No. 3, pp. 18-G5), " On the Food of Young Fishes" (No. 3, pp. 6(3-79), 

 "The Food of the Smaller Fresh- Water Fishes" (No. 6, pp. 65-94), 

 The First Food of the Common White-fish, (No. 6, pp. 95-109), and 

 "Studies of the Food of Fresh-Water Fishes" (VoUI., Art. VII., 

 pp. 433-173). 



