THE NATIVE FISHES OF IOWA. 



By SETH E. MEEK, M.S. 



In the following paper is given a list of the native fishes of 

 Iowa, with an analytical key by which they may be distin- 

 guished. A few notes are added concerning the habits, the 

 economic value, and geographical distribution of each species. 



A fish is a cold-blooded vertebrate, living in the water, and 

 breathing by means of gills. The exoskeleton is developed as 

 scales or bony plates. The limbs, if present, are developed as 

 fins. On the median line of the body is usually one or more 

 fins consisting of spines and cartilaginous rays, usually joined 

 by a membrane. The fins on the median line of the back are 

 the dorsal fins. The one on the median line of the belly is the 

 anal fin. The fins homologous with the arms or the fore legs 

 of other animals are the pectoral fins, those homologous with 

 the hind legs are the ventral fins. Usually along the side 

 extending from the shoulder to the caudal fin (tail fin) is the 

 lateral line. At each side of the head are the gill openings, 

 these are covered by the gill covers, which are composed of 

 several pieces. The upper piece is the opercle, below this 

 and forward is the sub-opercle. The edge bordering the 

 cheek is the pre-opercle, this is sometimes serrated on its edge. 

 The thin membrane below the sub-opercle is the branchios- 

 tegal membrane, its cartilaginous supports are the branchios- 

 tegal rays. 



The gills are supported on cartilaginous arches. On the 

 inner side of the first gill arch are the gill rakers. 



The scales are cycloid when smooth on their posterior 

 border, ctenoid when toothed or spiny. 



The classification of fishes is based chiefly on osteological 

 characters, but in the present paper only such characters are 

 used as will enable one to identify the species known at pres- 



