ETHEOSTOMATID^. — LXXXIX. 217 



b. Upper jaw not protractile; vomerine teeth present. 

 c. Moutli narrow, inferior, overlapped by a tapering, trun- 

 cate, more or less "pig-like" snout; ventral plates pres- 

 ent, or, if fallen, a naked strip ; body elongated ; 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 vertebrae in increased 

 number, more than 20 in front of anus ; well-devel- 

 oped teeth on vomer and palatines ; dorsal spines 12 

 to 15 ; tins never tuberculate. . Alvordius, 4. 



ee. Body and head shortened ; vertebrjie 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. . . Hadropterus, 6. 



bb. Upper jaw protractile, a distinct furrow separating it from 

 the skin of the forehead. 



/. 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 (in adult males?) greatly elevated, reaehing to base 

 of caudal fin Imostoma, 7. 



ff. 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 small sub- 

 inferior mouth ; cheeks naked; opercles scaly; anal fin 

 not enlarged Riieocrypta, 8. 



f f 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. 



