46 U.S. NATIONAL MUSEUM BULLETIN 2 82 



Wisconsin: IjMMZ 64512, 64531, 64649, 64898, 72379, 73568, 73644, 73702, 

 73717, 73803, 74209, 74347, 74778 (outlet Mary L., Marinette Co.), 74836 (outlet 

 Nocquebay L., SW. of Crivitz, Marinette Co.), 76164, 76691, 77058, 77142, 

 77630, 77773, 77789, 77875, 78096, 78126, 78210, 78257, 78297, 78310, 78353, 

 78395, 78448, 78461, 95976, 95984, 96005, 96078, 96175, 96214, 96263; SU 14985; 

 CNHM 35648-9. 



CANADA: Manitoba: UMMZ 180538 (Millers Cr., sec. 34, T. 30, R. 5 E. 

 Prin. mer.). Ontario: UMMZ 130869, 130915, 130939, 130980. Quebec: UMMZ 

 136396 (L. St. Louis of St. Lawrence R., at Maple Grove, near Lariviere dock, 

 Montreal). 



Type. — Silurus gyrinus was described from the Wallkill River. 

 Jordan (1877d, p. 71) did not list the type-specimen among those 

 that he examined, and it is presumably not extant. 



Diagnosis. — Noturus gyrinus, as well as A^. exilis and A^. lachneri, 

 in the subgenus Schilbeodes has a terminal mouth (jaws subequal) 

 and typically ten preoperculomandibular pores over much of its 

 range. In contrast to A^. exilis the pectoral spine is deeply grooved and 

 nonserrated, and there are modally eight pelvic rays, except in the 

 central Gulf drainage. From A^. lachneri, gyrinus is characterized by 

 the separation of the anterior ends of the infraorbital and supra- 

 orbital canals (2 internasal pores) and fewer fin rays and vertebrae. 

 Also characteristic are the high procurrent caudal rays, many of 

 which may be branched and a low (1.5, usually 1.2 or less) ratio of 

 the distance from the end of the adipose fin to the tip of the caudal 

 fin stepped into the distance from the origin of the dorsal fin to the 

 end of the adipose fin. Except for the lower, more lightly pigmented 

 surfaces, the body and fins are nearly uniformly colored. 



Description. — Other counts and measurements are given in tables 

 17 to 26. Body shape somewhat variable, usually short and chubby, 

 deepest at or in front of dorsal fin, but some individuals, especially 

 in the southern states, are very elongate; head rather deep; skull 

 arched and rounded above; lower jaw terminal; premaxillary tooth 

 patch with lateral edges and posterior corners rounded (not angulate), 

 the overall lateral dimension of the band of teeth notably greater 

 than in other species of Noturus, about 3 or 4 times the anterior- 

 posterior measurement; humeral process distinct, about as long as 

 the width of the shaft of the pectoral spine, its tip usually turned 

 slightly inward; eye very small, 3.5 to 5.0 times in snout; pectoral 

 spine without serrae, but frequently with some smooth bumps on 

 its posterior edge near base; the spine angulate in cross section, 

 very deeply grooved, their depth nearly that of the spine, their 

 length variable, but along most of the spine; imbedded in these grooves 

 and surrounding the spine is a mass of grayish white, flaky material; 

 dorsal spine stout; adipose fin high, widely united to the long procur- 

 rent caudal rays, many of which may be branched; caudal fin some- 



