ETHEOSTOMATIDA. 13 
b. Upper jaw not protractile ; vomerine teeth present : 
ce. Mouth narrow, inferior, overlapped by a tapering, truncate, more or less pig- 
like snout; ventral plates present, or, if fallen, a naked strip; body elon- 
gated ; cheeks and opercles scaly ; size largest of all the darters, PERCINA, 3. 
cc. Mouth wider, terminal, the upper jaw being but little longer than the lower: 
d. Ventral plates developed, or, if fallen, middle line of belly with a naked strip: 
e. Body and head elongate; the vertebre in increased number, more than 
20 in front of anus; well-developed teeth on vomer and palatines ; dorsal 
spines 12 to 15; fins never tuberculate...............---..ALVORDIUS, 4. 
ee. Body and head shortened ; vertebra fewer, less than 20 in front of anus ; 
a few minute teeth on vomer and none on palatines; dorsal spines 10 to 
12; colors brilliant, the male in spring with the lower fins tuberculate, 
Ericosma, 5. 
dd. Ventral plates not developed ; middle line of belly scaled like the sides, 
HapROrTeERvs, 6. 
bb. Upper jaw protractile, a distinct furrow separating it from the skin of the 
forehead : 
f. No ventral plates; posterior ventral region scaled; anterior region largely 
naked; vomer well toothed; head and body stout and heavy; cheeks 
and opercles scaly; anal fin (iu adult males?) greatly elevated, reaching 
bozbasclot cand alifimes=s20)_ 2b sss macon eae oe ees e aseeee. IMOSsTOMA, 7. 
Jf. Ventral plates well developed, or, if fallen, a naked strip; vomer with a few 
minute teeth; palatines naked; body rather slender, with rather narrow 
head and smaller subinferior mouth ; cheeks naked ; opercles scaly ; anal 
fimeno tremlarredWast ret as tesa sos ese Sae sete wise Sele ee creicie RHEOCRYPTA, 8. 
+t. Second dorsal considerably larger than anal fin; no ventral plates, the middle 
line of the belly always covered with small scales like those of the sides: 
g. Upper jaw protractile : 
h. No teeth on vomer or palatines; mouth small, contracted, subinferior ; head 
short and thick, with swollen cheeks; spinous dorsal rather long; cheeks 
and opercles scaly ; anal spines strong; body elongated, little compressed, 
DIPLEsIUM, 9. 
hh. Vomerine teeth present ; dorsals contiguous, but distinct ; the spinous dor- 
sal short; head narrowed; the mouth rather small, horizontal, sub- 
inferior : 
i. Anal spines two, well developed ; the first the longer....-.--.-- ARLINA, 10. 
ii. Anal spine single, more or less obscure and undifferentiated from the soft 
: DAS ee aes aimine nya ena oei tae elsstiate (ind co Nemine ala oremia snail etn BOLEOSOMA, LI. 
gg. Upper jaw not protractile: 
j. Dorsal fins well apart; body fusiform, little compressed ; scales large; cheeks 
and opercles scaly; mouth small, horizontal, subinferior (as in Boleosoma) ; 
caudal peduncle rather slender .-.--....---..--.-....... Nanostoma, 12. 
jj. Dorsal fins slightly connected at base; body rather short, deep, strongly 
compressed; scales small; cheeks naked; mouth rather large, oblique 
(as in Pecilichthys); caudal peduncle deep ...--.-.----- NOTHONOTUS, 13. 
***, Lateral line incomplete or wanting; no ventral plates; upper jaw not protractile; 
second dorsal larger than anal; vomer with teeth: 
k. Lateral line present on anterior part of body: 
l. Dorsal fins contiguous, the membrane of the first reaching to the base of the 
second : 
m. Spinous dorsal fin well developed, two-thirds or more the height of the 
second ; the spines graduated, never ending in little fleshy knobs; lateral 
line extending more than half the length of the body ; mouth moderate, 
the upper jaw usually a little the longer; opercles scaly; cheeks naked; 
body rather short and deep. .............---------0- Pa@cILICHTHYS, 14. 
