LAMPREYS AND FISHES OF INDIANA. 265 



Family PERCID.E. 

 THE PERCH- LIKE FISHES. 



Body short or long, compressed or terete. Mouth various ; teeth on 

 jaws and usually on vomer and palatines. Scales ctenoid. Lateral line 

 present or absent. Maxillary without supplementary bone. Branchios- 

 tegals, six or seven ; gills four, a slit behind the last. Dorsal fins two, 

 the anterior of six to fifteen spines ; anal with one or two spines. 



This important family of fishes contains a doubtful number of genera, 

 and these have been assigned to two sub-families. One of these, the 

 Etheostomatinw, consists of a large number of mostly small, but vigorous 

 and highly adorned fishes, characterized technically by the rudimeutary 

 condition of the pseudobrancbise and air bladder. The other sub-family, 

 the Percimc, have these organs well developed, and besides attain a large 

 size and are of considerable economical importance. 



The Etheodomaiimc are abundant in all our clearer streams. They are 

 small, have large pectoral fins, are usually highly colored, and hide among 

 stones or repose on the bottom. They have until recently been divided 

 into a great number of genera on trivial characters. More recently the 

 authoi-ities on matters ichthyological have united all these genera into a 

 single one, Etheostoma. This, while apparently a progress to the other 

 extreme, may yet be justified. I have tho.ught best here to take a median 

 course. The difiiculties in the way of establishing genera among the nu- 

 merous species are many. 



* 



KEY TO THE GENERA OF PERCID.E 



A. Adult size small. Pseiidobrauehise and air-bladder imperfect or 

 wanting. Preopercle entire. Branchiostegals six. (Etheosfo- 

 matina'. ) 



1. Premaxillaries protractile, sometimes only slightly so. 



a. Body elonyated ; with at least the belly devoid of scales, 

 often but few scales present; body in life translucent. 



. Ammocrypta, p. 266. 

 aa. Body well covered with scales. 



b. Vomer with teeth ; maxillary not bound to preorbital. 



Boleosoma, p. 267. 



bb. Vomer without teeth ; maxillary closely bound by 



skin to the preorbital. Diplemtm, p. 270. 



2. Premaxillary not protractile. 



a. Mouth overhung by a pig-like snout. Scales of the lateral 



line about 90, Percina, p. 271. 



aa. Mouth not decidedly inferior, often terminal ; scales of 



lateral line 35 to 85. Etheostoma, p. 272. 



