SILUKID^. 97 



Pectoral fins with a sharp spine, either smooth, grooved, or dentate be- 

 hind, the size and armature of the spine affording good specific characters. 



The anus is situated some distance in advance of the anal fin. 



The lateral line is complete. 



The yoturi may be known at once by the peculiarities of the adipose and 

 caudal fins. The genus is rather less homogeneous than any of the others. 



Two subgeneric sections are recognizable: — 



Noturus. Size hivge ; intermaxillary band of teeth with a backward 

 process; pectoral spine nearly smooth within, sharply retrorse-serrato 

 externally ; a keel between dorsal and adipose fins. 



Schilbeodes. — Size moderate or small; intermaxillary band of teeth 

 without backward process; pectoral spine more nearly smooth exter- 

 nally, grooved or else serrate within j back not distinctly keeled. 

 ANALYSIS OF SPECIES. 



•. Premaxillary band of teeth with a strong backward process on each side (Noturus) : 

 a. Body elongate ; head depressed, broad, and flat, nearly as broad as long ; middhs 

 region of body subcyliudrioal ; tail compressed ; head about 4J in length ; 

 width of head 5^ ; depth 5j in length ; distance to dorsal about 3 in length ; 

 barbels, short ; a strong keel on back behind dorsal, leading to adipose liu ; 

 adipose fin deeply notched; dorsal spine very short, pectoral spine retrorsely 

 serrate in front, slightly rough or nearly entire behind ; its length three times 

 in distance from snout to dorsal; anal rays about 16; color nearly uniform 

 yellowish-brown, in northern specimens blackish above, slightly mottled ; 

 tins yellow-edged ; size very large, reaches a length of more than a fooD 



Flavcs, 23. 



•*. Preraaxillary band of teeth without lateral backward processes (Schilheodea) : 

 t. Pectoral spine dentate-serrate behind, more or less roughened in front; adipose 

 fin notched : 

 6. Pectoral spines shortish, nearly straight, about one-third length of head ; the 

 serratures weak, less than half the diameter of the spine; body elongated 

 its depth hi to 7 in length ; the head very much depressed ; anal 14 to 17 ; 

 colors nearly uniform, somewhat mottled ; fins more or less dark-edged, 

 c. Pectoral spine retrorse-serrate without, weakly serrate within ; head very 

 broad, flat, and thin; upper jaw projecting; head about 4i in length, 

 depth 0; dorsal fin one-fourth higher than long; distance from snout to 

 dorsal about 2| in length ; length of pectoral spine 2| in same distance ; 

 dorsal much nearer anal than snout ; anal rays It) to 20 ; size large (reaches 

 the length of nearly a foot) ; colors rather dark ; dorsal and caudal fins black- 



raargined \ Insignia 24. 



cc. Pectoral spine slightly retroise-serrate without, with about six small straigh 

 teeth within, which are not one-third the diameter of the spine in length ; 

 head small, not very broad, but thin and depressed ; its width tH to 6 in 

 length of body ; jaws nearly equal ; head 4} in length, depth 5J to Gi ; dorsal 

 scarcely higher than long ; distance from snout to dorsal about -.^ •» lenfith ; 

 pectoral spine 3^ to 4 in this distance ; dorsal spine low, nearer snout than 

 anal ; anal rays 14 or 15 ; size small ; color pale ExiLis, 23. 



Bull. N. M. No. 10—7 



