170 REPORT OF STATE GEOLOGIST. 



fishes, for the most part now widely separated, but between which, like 

 intercurrent strings, there yet remain a few somewhat anomalous fam- 

 ilies. 



Orders of PHYSOSTOMI. 



* Body of normal, fish-like form ; veutrals rarely wanting. 



a. Skin naked, devoid of scales ; barbels about mouth ; pectorals 

 and dorsal each with spine. (Cat-fishes.) 



Nematognathi, p. 170. 

 aa. Skin usually furnished with scales ; barbels rarely present. 



b. Lower pharyngeals falciform, armed with a few teeth in 



from one to three rows ; no teeth in the mouth. (Suckers 



and minnows.) Eventognathi, p. 181. 



bb. Lower pharyngeals not falciform, and without enlarged 



teeth. (Moon-eyes, herrings, shad, white-fish, etc.)* 



Tsosjoondyli, p. 223. 



c. Shoulder girdle furnished with a precoracoid arch. 



cc. Shoulder-girdle without precoracoid arch ; jaws with 



teeth. (Blind-fishes, toothed minnows, mud minnows 



and pikes.) Haplomi, p. 233. 



'i^* Body greatly elongated and snake-like ; ventrals wanting. Eels. 



Apodes, p. 243. 



Order 5. NEMATOGNATHI. 



THE CAT-FISHES 



Body possessing the normal, fish-like form. The skin is naked, without 

 scales, but some exotic forms possess bony scutes. The maxillaries are 

 rudimentary, forming the base of the two longest barbels. Suboperculiim 

 absent. The four anterior vertebrae are coalesced and connected with the 

 organs of hearing. It contains with us only the following family : 



* The following remarks concerning fishes belonging to the two orders, IsospondyU and 

 Haplomi, may be of assistance to students in identifying our Indiana species, but these 

 statements, it must be understood, do not apply to all extra-limital species. 



Our isospondylous fishes are more or less compressed, both as to head and body. In all, 

 the head is devoid of scales. All possess an adipose fin, except the gizzard-shad (Dorosoma) , 

 the shads {Gin pea), which have no teeth, or very feeble ones, and the moon-eye (Hiodon), 

 which has a very complete dentition, including teeth on the tongue. The dorsal fin is 

 usually medium in position (well behind in ^todoii, however). The gill -rakers are often, 

 but not always, long. The lateral line of pores is usually present, but wanting in the shads 

 and the gizzard-shad. 



The Haplomi, on the other hand, have the body compressed behind, but rather wide and 

 depressed in front, and the head is rather flat. The head always has scales on some part, 

 •except in the case of the blind cave-fishes {Ainblyopsidiv) . There is never an adipose fin 

 present, while the dorsal is far back in the region of the anal. The lateral line is wanting, 

 •or nearly so, except in the pikes. 



