1028 Bulletin 47, United States National Museum. 



number; a black caudal spot; dorsal and caudal mottled. Lakes of 

 northern Indiana, Michigan, Wisconsin and northward to Lake Superior; 

 the common form in the Great Lakes. The typical zebra is well distin- 

 guished from caprodes, but specimens variously intermediate have been 

 obtained in Illinois by Dr. Forbes and in the Potomac by Dr. Bean. 

 (zebra, a striped wild horse ; from the color.) 



Pileoma zebra, AGASSIZ, Lake Superior, 308, 1850, Lake Superior; VAILLANT, Becherches, 48, 



1873, with plates. 

 Percina manitou, JORDAN, Proc. Ac. Nat. Sci. Phila., 1877, 53, Lake Manitou, Rochester, 



Indiana. 

 Percina caprodes manitou, JORDAN & GILBERT, Synopsis, 500, 1883. 



466. HADROPTERUS, Agassiz. 

 (BLACK-SIDED DARTERS.) 



Hadropterus, AGASSIZ, Amer. Journ. Sci. and Arts, 1854, 305, (nigrofasciatus). 



Etheostoma,* AGASSIZ. Amer. Journ. Sci. and Arts, 1854, 305, (''blennioides" (not of RAFINESQUE 



= aspro). 



Alvordius, GIRARD, Proc. Ac. Nat. Sci. Phila., 1*59, 68, (maculatus). 



Plesioperca, VAILLANT, Recherches sur Poissous des Eaux Douces, Etheostomatina, (anceps). 

 Ericosma, JORDAN & COPELAND, Bull, x, U. S. Nat. Mus., 8, 1877, (evides). 

 Serraria, GILBERT, Proc. U. S. Nat. Mus., 1884, 205, (scierus). 



Body rather elongate, compressed or not. Mouth rather wide, terminal, 

 the lower jaw included, the snout above not protruding beyond the pre- 

 maxillaries, which are not protractile. Teeth on vomer and usually on 

 palatines, also. Gill membranes separate or more or less connected. 

 Scales small, ctenoid, covering the body. Belly with a median series of 

 more or less enlarged spinous plates or ctenoid scales, which in most spe- 

 cies fall off at intervals, leaving a naked strip; in some species persistent 

 and but slightly enlarged ; sides of head scaly or not ; lateral line com- 

 plete or nearly so. Fins large, the soft dorsal smaller than the spinous or 

 the anal ; anal spines 2 (one of them very rarely obsolete) ; dorsal spines 

 10 to 15. Ventral t fins more or less widely separated, especially in species 



* The name Etheostoma can not be used for this group as none of its species was known to 

 Raflnesque, who based the genus Elheostoma on caprodes, blennioides, and flabeUare. 



f This character of the separation of the ventrals " by an interspace equal to the width of their 

 base" was first introduced as a generic feature by Dr. Boulenger (Cat. Teleostean Fishes, I, 45). 

 Itisused by him to separate Percina (= Percina + Alvordius) from Etheostoma (= Etheostoma + Hypo- 

 homus + Serraria -f Hadropterus proper + Piccilichthys -\- Boleichthys + Alvarius, etc.), in which the 

 ventrals are said to be " separated by an interspace considerably less than the width of their 

 base." In like manner Boleosoma (including Coltogasler) is separated from Ulocentra and Diplesion, 

 the former having the ventrals widely separated. In Ammocrypta the interspace is equal to the 

 width of the base. To ascertain the value of this character we have, with the assistance of Dr. 

 Meek, examined most of the species o f Etheostomiiise. We find that in the extreme forms, Percina, 

 Crystallaria, Boleosoma, Ammocrypta on the one hand, the ventrals are widely separated, as stated 

 by Dr. Boulenger. On the other hand, in species related to Etheostoma flabeUare and E. cxnileum, 

 they are very close together. Between these extremes, however, we find every gradation. This 

 character, like other characters, shading off by degrees, and many of those species described by 

 Dr. Boulenger as having the fins close together, would be placed by us rather with the others. 

 The comparison of the interspace with the width of the base of the finis not wholly satisfactory, 

 as the base of the fins appears broader in the males with enlarged rays and narrower in the 

 young. In general those species with the most elevated crania have the ventrals nearest 

 together, a character usually going with small anal fin and short first dorsal, except among the 

 allies of Ammocrypta and Boleosoma, The species examined by us may be roughly placed in four 

 groups, thus: 



