1887.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 55 



and pectoral fins ; (2) a single soale only, firmly embedded in middle 

 of breast; (3) an additional patch of scales occupying region between 

 base of pectoral fins and gill opening; (4) this patch produced down- 

 ward and encroaching on the breast proper, which may then have fur- 

 ther a transverse band of scales or a V-shaped patch in front of ventral 

 fins. Some or all of these stages have been found in material from the 

 Eolling Fork and the Rockcastle Eiver, in Kentucky, the Chickasawha 

 Eiver, in Mississippi, and the Little Miama River, in Ohio. The ma- 

 jority of specimens show the breast naked and a patch of scales jjresent 

 in advance of pectoral fins. In no specimen examined has the breast 

 been found completely invested. 



What is true of the squamation of the breast is true also of the 

 cheeks and opercles. Specimens from the Little Miami River and from 

 Florence, Ala., have these regions scaled, but the scales vary greatly 

 in condition. In some individuals the scales are ctenoid and imbri- 

 cated, like those on the body; in others they are almost completely 

 embedded in the skin, the spiny points only projecting; in still others 

 they have become thin and weak, are no longer imbricated, and show 

 only cycloid concentric rings. A further stage in this last process 

 would doubtless result in their absorption and entire disappearance. 

 Specimens from the Rolling Fork have the cheeks usually naked, the 

 opercles more or less completely scaled ; from the Rockcastle have 

 cheeks and opercles either partly or wholly naked, the scales on cheeks 

 being the first to disappear ; from the Washita River, Ark., have cheeks 

 and opercles, entirely scaled, or j>artly or wholly naked. 



It seems at least possible that zonale is tending toward entire loss of 

 scales from head and breast, this tendency being independent of local 

 conditions, and therefore pretty equally exhibited throughout the range 

 of the sjiecies. 



9. Etheostoma (Rhothoeca) blennius Gilbert & Swain, sp. nov. 36187. 



Body exceedingly robust, little compressed, the ventral outline more 

 strongly arched than dorsal outline ; greatest depth opposite front of 

 spinous dorsal, the two profiles thence converging rapidly backwards to 

 form the rather long, slender, caudal peduncle. Head very deep, with 

 subvertical cheeks, broad below, narrowing upwards and forwards. 

 Profile from nape to middle of iuterorbital space nearly horizontal, 

 thence abruptly and very obliquely decurved to tip of snout. Middle 

 of eye equidistant from tip of snout and front of nape. Greatest depth 

 of preorbital two-sevenths length of head. 



Mouth very small, subinferior, the lower jaw included. Length of 

 maxillary equaling distance from tip of snout to anterior nostril. Pre- 

 maxillaries not protractile, the fold of upper lip interrupted by a very 

 narrow frenum, as is the case in some specimens of Etheostoma simoterum, 

 to which blennius seems closely related. Vomer with teeth. Opercular 

 spine very little developed, the opercle terminating in a flat point, 



