ETHEOSTOMA 303 



those along its sides are small and inconspicuous. In an aquarium 

 with sand on the bottom, it was seen to bury itself in a few seconds by 

 first stirring up the sand with rapid beats of its tail, as it stood liter- 

 ally upon its head, then lying still as the sand settled again, and 

 quietly putting out its nose and eyes, leaving only these and the 

 front of its head to be seen. Notwithstanding its peculiar habits 

 and its nice adaptation to a special environment, it is among our 

 group of most typical darters, its most frequent associate in our 

 collections being Hadroptcnts phoxocephalus, and next to this, Ha- 

 dropterns aspro. 



Its food seems remarkably uniform, consisting, like that of so 

 many other darters, of dipterous larvae, mainly Chironomus, and 

 larvae of Mav-flies, the former largely preponderating in the speci- 

 mens we have studied. 



Genus ETHEOSTOMA Rafinesque 



Bodv robust or rather elongate, considerably compressed, or greatly 

 so; mouth varying in size, terminal or subinferior; premaxillaries not 

 protractile; teeth usually present on vomer and palatines; vertebra? i3 

 to 39, usually 36 (15+21); pyloric caeca 3 or 4; belly with ordinary 

 scales. Species numerous, about 30; size small; coloration various, often 

 brilliant. 



A large group, difficult to characterize, including a wide range of 

 forms, which, however, agree in having the premaxillaries non-pro- 

 tractile, and differ from all the preceding genera (except possibly 

 Diplesion) in having the cranium more elevated behind the eyes — 

 fl-shaped.* These fishes are, as a rule, more or less compressed, and 

 deeper bodied than such forms as Cottogaster, Boleosoma, and Ha- 

 dropterus. In this group are found our most brilliantly colored- 

 darters, bright red and blue in gaudy display on both body and 

 fins prevailing in the dress of many species. 



Key to the Species of ETHEOSTOMA found ix Ii.i.ixois 



a. Lateral line usually compli te, i iccasionally 2 to 6 pi ires lacking. 



b. Gill-membranes joining broadly across the isthmus, distance from le 



to their angle 4(i to 50 pei cenl greater than from muzzle to back oi 



i irl .it ' zonale. 



bb. Gill-membranes scarcely connected, distances to angle and to bai I oi orbil 

 no1 far from equal camurum. 



*The forms (flabellare, obeyense, and squamiceps) with low dorsal fin and blai I. 

 humeral spot (see key) senn to agree in having the parietals less an hed than is 

 usual in Etheostoma, and shaped in cross-sectii in more nearly as in Boleosoma. 



