CATFISH GENUS NOTURUS RAFINESQUE 9 



Adipose notch or posterior end of adipose fin. — This point 

 is variable. If the adipose fin forms a free flap at its posterior end, 

 measurement is to the tip of the flap; if only a notch exists near the 

 junction of the adipose and caudal fins, measurement is to the lowest 

 point in the concavity; if the fin is separated from the caudal fin, the 

 measurement is to the rear end of the adipose tissue. 



Caudal peduncle depth. — The least depth of the caudal peduncle 

 below the adipose fin. 



Caudal peduncle length. — The measurement is from the base 

 of the last anal ray to the midbase of the caudal fin. 



Dorsal origin. — The dorsal origin is regarded as the apex of the 

 notch in the imbedded, plate-like spine preceding the dorsal spine. 



Dorsal spine length. — Measurement is from the dorsal origin 

 to the tip of the long spine. 



Pectoral spine to humeral process tip. — The distance is from 

 the anterior base of the erected pectoral spine to the free end of the 

 posterior process (spine) of the clei thrum (humeral process). 



Predorsal length. — This length is from the dorsal origin to 

 the tip of the snout. 



Snout to anal fin. — Measurement is from the tip of the snout to 

 the origin of the anal fin. 



Snout to pelvic fin. — The distance is from the tip of the snout 

 to the insertion of the oute r pelvic ray. 



The Family Ictaluridae 



Members of the family Ictaluridae are found in the fresh waters 

 of eastern North America, from the Hudson Bay and Saint LawTence 

 drainages of Canada southward through most Atlantic Ocean tribu- 

 taries to the Usumacinta River, Guatemala; in Mexico, they occur 

 in some of the streams flowing into the Pacific Ocean. Several of the 

 economically important species have been introduced into waters 

 in temperate countries throughout the world. 



Although China was once included in the range of the family, no 

 recent worker on the ichthyological fauna of China has reported any 

 species referable to the Ictaluridae. These old reports probably stem 

 from erroneous labels or misidentifications. 



The Siluriformes or Nematognathi, to which the Ictaluridae be- 

 long, is characterized by the absence of parietal and opisthotic bones 

 as well as the subopercle (unless the large, broad upper branchiostegal 

 ray represents the subopercle). In most catfishes, the maxilla is 

 greatly reduced; a vestige of this element remains as a small, rod-like 

 structure that projects into the base of the maxillary barbel in the 

 Ictaluridae. 



