SILURIDZ. 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 Noturi 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 large; intermaxillary band of teeth with a backward 
process; pectoral spine nearly smooth within, sharply retrorse-serrate 
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; 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; middle 
region of body subcylindrical; tail compressed ; head about 44 in length ; 
width of head 54; depth 53 in length; distance to dorsal about 3 in length ; 
barbels, short; a strong keel on back behind dorsal, leading to adipose fin ; 
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 ; 
fins yellow-edged; size very large, reaches a length of more than a foot 
FLAVUS, 23. 
** Premaxillary band of teeth without lateral backward processes (Schilbeodes) : 
t. Pectoral spine dentate-serrate behind, more or less roughened in front; adipose 
fin notched : 
b. 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 54 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 4} in length, 
depth 6; dorsal fin one-fourth higher than long; distance from snout to 
dorsal about 22 in length; length of pectoral spine 2? in same distance ; 
dorsal much nearer anal than snout; anal rays 16 to 20; size large (reaches 
the length of nearly a foot); colorsrather dark; dorsal and caudal fins black- 
AN ALPINE Oe aed eae Se sree nasa eee ences aoe spo cal lami aia ab o.as INSIGNIS, 24. 
ce. Pectoral spine sli ghtly retrorse-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. 5} to 6 in 
length of body ; jaws nearly equal ; head 4} in length, depth 53 to 64; dorsal 
scarcely higher than long ; distance from snout to dorsal about 3 in length ; 
pectoral spine 34 to 4 in this distance; dorsal spine low, nearer snout than 
anal; anal rays 14 or 15; size small; color pale......-.-...----. EXILIs, 25. 
BULL. N. M. No. 10—7 
