CATFISH GENUS NOTURUS RAFINESQUE 11 



An air bladder is present in all ictalurids except Satan and Troglo- 

 glanis. It is attached to the vertebral complex by connective tissue 

 but is never encased in bone. The testes of Noturus and Pylodictis 

 are grossly similar in shape to those of Ictalurus, as described by 

 Sneed and Clemens (1963). 



The larger species of Ictalurus and Pylodictis are of considerable 

 economic importance, both in sport and commercial fisheries. Small 

 catfishes are sometimes used for bait, presumably because of their 

 relative hardiness. 



The young of Ictalurus and members of the genus Noturus are 

 generally reputed to be venomous (Reed, 1907 and 1924b), introduc- 

 ing a poison with their sharp spines. The nature and source of the 

 presiuned poison should be carefully investigated. A gland, reputedly 

 the poison gland, is situated just beneath the skin, immediately below 

 the humeral process (posterior extension of the cleithrum) and opens 

 directly to the surface through a large pore. It contains an amber 

 colored, jelly-like material. The pore is reduced in size or closes with 

 age in the larger ictalurids but remains open in Noturus. It is remote 

 from the erect pectoral spine but the spine may closely approximate 

 the pore when folded against the body. Flaky material surrounding the 

 spines and imbedded in their grooves should also be investigated for 

 possible toxicity. 



Fossil representatives of Ictalurus are known from various Tertiary 

 deposits — at least the Lower Pliocene (Hubbs and Hibbard, 1951) — 

 indicating that the genus has had a long history, and Pylodictis has 

 been recorded from the Pleistocene (Uyeno and Miller, 1962). Although 

 fossUs of other groups in the family are yet to be found or recorded, 

 it is presumed that their history has been lengthy. 



The members of this family are most active at night. The madtoms 

 and stonecats are especially nocturnal in habits; they are seldom seen 

 and infrequently captured by ordinary collecting methods in the day- 

 time. At night they may literally swarm over the area where they 

 appeared to be uncommon in the daytime. These observations point 

 to the cryptic habits of many of the species and to their occasional 

 great abundance in favored habitats. Hooper (1949 and 1951) has 

 indicated something of the abundance of one species in Demming 

 Lake, Minnesota. He estimated at least 8,600 individuals (88 pounds) 

 of Noturus gyrinus in a lake of 12.5 acres. 



The Sensory Canal System 



Plate 1 

 The sensory canal system provides important indications of inter- 

 relationships in fishes. A short article by CoUinge (1895) compared the 

 canals in certain Old World catfishes; Pollard (1892) gave comparative 



298-943 O— 169 2 



