486 contributions to north american ichthyology iv. 



Family LXXXV.— PERCID^. 



{llie Perches.) 



Body more or less eloDgate, terete or compressed, covered more or less 

 comijletely with rather small, ctenoid, adherent scales. Lateral line 

 usually i)resent, not extending on the caudal fin. Mouth terminal or 

 inferior, small or large, the premaxillaries protractile or not ; maxillaries 

 large or small, without distinct supplemental bone. Jaws, vomer, and 

 palatines with bands of teeth, which are usually villiform, but some- 

 times mixed with canines; occasionally the teeth on the vomer or pala- 

 tines are absent. Head naked, or more or less scaly ; preopercle entire 

 or serrate ; opercles usually ending in a flat spine. Branchiostegals 6 

 or 7. Gills 4, a slit behind the fourth ; gill-membranes free or connected, 

 not joined to the isthmus ; gill raters slender, toothed ; pseudobranchiae 

 small, or glandular and concealed, or altogether wanting ; lower j^haryn- 

 geals separate, with sharp teeth. Fins generally large ; two dorsals, 

 the first of 6 to 15 sjiines ; anal flu with one or two spines (three in 

 Percichthys, a fresh- water genus from Chili). Ventrals thoracic, I, 5; 

 jiectorals often very large ; caudal lunate, truncate or rounded. Anal 

 l^aiDilla often present. Air bladder small and adherent, often entirely 

 wanting. Pyloric cceca few. Vertebrae, 30 to 45. 



Genera about 22 ; species, 90 to 100 ; inhabitants of the fresh waters 

 of cool regions, most of them being American and nearly all belonging 

 to the fauna of the United States. The great majority of the species 

 belong to the sub-family of Utheostomatinw, the Darters, all the species 

 of which grouj) are American. They are among the most singular and 

 interesting of our flshes. They difier from the typical Percince in their 

 small size, bright colors, and large fins, and mvve technically in the 

 rudimentary condition of the pseudobranchitB and the air bladder, both 

 of which organs are usually inappreciable. The preopercle is unarmed, 

 and the number of branchiostegals is six. An anal papilla is likewise 

 developed, as in the Gobiklfv, to which group the Darters bear a consid- 

 erable superficial resemblance, which, however, indicates no real affinity. 

 The relations of the Darters to the Perches have been aptly expressed 

 by Professor S. A. Forbes: 



"Given a supply of certain kinds of food nearly inaccessible to the 

 ordinary fish, it is to be expected that some fishes would become 

 esx)ecially fitted for its utilization. Thus the Ftheostomatince as a grouj) 



