FAMILY GOBIDA. 153 
GENUS GUNNELLUS. Cuvier. 
Body elongated, much compressed. Head oblong. Mouth small. Teeth velvet-like, or in 
cards. Dorsal rays spinous throughout. Ventrals excessively small, and reduced often 
to a single spine. 
Oxs. This genus was first named Centronotus by Bloch, but this name has been applied 
by Lacépéde to another group among the Scombride. Some English ichthyologists have con- 
tinued to use the badly characterized genus Murenoides of Lacépéde, without being aware, 
that while he retained the gunnellus of Linneus, he formed his new genus out of the B. 
murenoides of Sujef, not knowing that the two species were identical. 
THE AMERICAN BUTTER-FISH. 
GUNNELLUS MUCRONATUS. 
PLATE XIl. FIG. 36.— (STATE COLLECTION.) 
Ophidium mucronatum. Mutcniit, Lit. and Phil. Soc. Vol. 1, p. 249, pl. 2, fig. 1. 
Gunnellus mucronatus, Le Gonelle épineux. Cuv. et Vat. Hist. des Poiss. Vol. 11, p. 247. 
Blennius (Centronotus) gunnellus. RicHarpson, F, B. A. Fishes, Vol. 3, p. 91. 
Murenoides guttata, The Spotted Gunnel. Storer, Mass. Report, p. 65. 
Characteristics. Greyish, with a series of dusky oval rings along the sides. Dorsal not united 
to the caudal. Two short spines in place of the ventrals. Length four 
to seven inches. 
Description. Body elongate, linear, much compressed. No scales could be detected with 
a strong lens ; nor could I discover, in several specimens, any traces of a lateral line. Head 
small, subcarinate above; its length as one to nine compared with the total length. Mouth 
nearly vertical. Teeth acute, distant in both jaws, and a small group on the vomer ; lower 
jaw, when extended, longest. Branchial rays six, with a large branchial aperture. Body 
covered with a thick coating of mucus of the consistence of butter, from which is derived 
its popular name. 
g, subequal, commencing above the branchial aperture, and ex- 
tending nearly to the base of the caudal ; is composed of a very thick membrane, supported 
by from seventy-five to seventy-eight sharp spinous rays. The pectorals rounded and feeble. 
Beneath these, and slightly in advance, are two short and sharp spines, occupying the place 
of ventrals. The anal fin is nearly equal throughout its whole extent, not as high as the 
dorsal: it approaches still nearer to the caudal than the upper vertical fin, but is not con- 
nected with it. ‘The two anterior rays are short acute spines, the remainder soft and flexible. 
Caudal fin rounded. 
The dorsal fin single, long 
Fauna — Part 4. 20 
