TESSELLATED DARTER. 967 



ing for a short distance with great rapidity when disturbed, then resum- 

 ing its former position of quiescence. 



134. BoLEOSOMA 0LM8TEIJI (Storer) Agassiz. 

 Tessellated. Darter. 



Etheoatoma olmatedi, Stoker, Boat. Journ. Nat. Hist., iv, 1842, 61. 



Boleosoma olmaUdi, AwASSlz, Lake Superior, 1850, 299.— Storbe, Pish. Mass., 1867, 30. 



— CoPB, Proo. Amer. Pliilos. Soc, 1870, 268, and of nearly all authors. 

 Perca l^Percina) minima, HAUDBMAiJ, Journ. Acad. Nat. Soi.. viii, 1842, 330. 

 Boleosoma tesaellatum, DeKay, New York Fauna, Fisiies, 1842, 20.— Gunther, Cat. Pish. 



Brit. Mus., i, 1859, 77. 

 Soleoaoma maoulaticepa, Cope, Proc. Amer. Philos. Soc., 1870, 269. 



Desonption. — This species agrees with B. nigrum in all essential respects, except the 

 following : Cheeks aud operola scaly; lateral line complete, with about fifty scales in 

 its course; second dorsal comparatively long; D. IX, 14; A. I, 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 AUeghanies. In Ohio probably confined chiefly to tributaries of 

 Lake Erie. 



Habits. — Similar to those of Boleosoma nigrum. A species of the related 

 genus Vailldntia {Vaillantia camura, Forbes, Jordan), occurs in Illinois, 

 and may be looked for in Southern Ohio. It may be known from the 

 species of Boleosoma by its incomplete lateral line. 



Genus 73. DIPLESIUM. Eafinesque. 



Dipleaion, Rafikbsque, Ichthyologia Ohiehsis, 1820, 37. 

 Syoatoma, Agassiz, Amer. Journ, Sci. Arts, 1854, 305. 

 Diplmum, Jordan, Man. Vert., 1st Ed., 1876, 218. 



Type, Etheoatoma blennioidea, Eafinesque. 



Etymology, dia, two ; pleaion, 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 uwv- 

 ■ able, joined to the forehead mesially 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 ; vertebrae (D. ilennioidea) 19 plus 22 ; coloration largely green. 



135. DiPLESiuM BLENNioiDES (Rafincsque) Jordan. 



Crreen-sided Darter. 



Etheoatoma blennioidea, Rafinbsquk, Journ. de Phys., 1819, 419; loh. Oh., 1820, 37 (not 

 of Agassiz). 



