TESSELLATED DARTER. 967 
ing for a short distance with great rapidity when disturbed, then resum- 
ing its former position of quiescence. 
134. BoLEOSOMA OLMSTEDI (Storer) Agassiz. 
Wesseliated Darter. 
Ktheostoma olmstedi, STORER, Bost. Journ. Nat. Hist., iv, 1842, 61. 
Boleosoma olmstedi, Agassiz, Lake Superior, 1850, 299.—StorER, Fish. Mass., 1867, 30. 
—Copx, Proc. Amer. Philos. Soc. 1870, 268, and of nearly all authors. 
Perca ( Percina) minima, HALDEMAN, Journ. Acad, Nat. Sci.. viii, 1842, 330. 
Boleosoma tessellatum, DEKay, New York Fauna, Fishes, 1842, 20.—GUNTHER, Cat. Fish. 
Brit. Mus., i, 1859, 77. 
Boleosoma,maculaticeps, COPE, Proc. Amer. Philos. Soc., 1870, 269. 
Description.—This species agrees with B. nigrum in all essential respects, except the 
following: Cheeks and opercle scaly; lateral line complete, with about fifty scales in 
its course; second dorsal comparatively long; D. IX, 14; A. 1, 9; coloration essentially 
as in the preceding ; size somewhat larger. Length 3 inches. 
Habitat, New England to Wisconsin and south to Georgia, replacing B. nigrum north- 
ward and east of the Alleghanies. In Ohio probably confined chiefly to tributaries of 
Lake Erie. 
Habits.—Similar to those of Bolesesoma nigrum. A species of the related 
genus Vadllantia (Vaillantia camura, Forbes, Jordan), occurs in Illinois, 
and mzy be looked for in Southern Ohio. It may be known from the 
species of Boleosoma by its incomplete lateral line. 
GENUS 73. DIPLESIUM. Rafinesque. 
Diplesion, RAFINESQUE, Ichthyologia Ohiensis, 1820, 37. 
Hyostoma, AGassiZ, Amer. Journ, Sci. Arts, 1854, 305. 
Diplesium, JORDAN, Man. Vert., lst Ed., 1876, 218. 
Type, Htheostoma blennioides, RAFINESQUE. 
Ktymology, dis, two; plesion, near = two dorsals near together. 
Body elongate, subterete ; head very short and blunt, with tumid cheeks, the profile 
very convex; mouth small, inferior, horizontal; premaxillaries protractile, little mov- 
able, joined to the ferehead mesiaily by a slight frenum ; maxillary not protractile, ad- 
nate for most of its length to the fleshy skin of the preorbital; teeth in jaws strong; 
no teeth on vomer or palatines; gill-membranes broadly connected; scales moderate ; 
lateral line complete, no enlarged ventral plates; dorsal fins large, the spinous dorsal 
longer and lower than the second of about thirteen spines; anal smaller than second 
dorsal with two spines; vertebre (D. blennioides) 19 plus 22; coloration largely green. 
135. DIPLESIUM BLENNIOIDES (Rafinesque) Jordan. 
Green-sided Darter. 
Etheostoma blennioides, RAFINESQUE, Journ. de Phys., 1819, 419; Ich. Oh., 1820, 37 (not 
of Agassiz). 
