Billhead, the popular name of several species of cottoid fishes, principally of the genera coitus and acanthocottus, inhabiting both fresh and salt water. All were formerly confounded in the genus cottus, but Mr. C. Girard ("Smithsonian Contributions to Knowledge," vol. iii.) has separated them, restricting the genus coitus to the fresh-water species, while he gave the name acanthocottus to the marine species, more commonly called sculpins. These two groups are easily distinguished: the head of the former is smooth or nearly so, that of the other is tuberculous or armed with spines; the former is not found in salt water, nor the latter in fresh, though it is sometimes found in the brackish water of the mouths of the rivers. (See the work above alluded to, and the " Proceedings of the Boston Society of Natural History," vol. ih\, p. 183.) The most obvious characters are the following: In acanthocottus the opercular apparatus is armed with strong spines; the surface of the head, and often the circumference of the orbits, is similarly armed, or is serrated in various ways; the nasal bones are in some species surmounted by a ridge or spine; the head is high and broad, occasionally deformed, with very large eyes and an immense mouth; the body is without scales, the back often arched, and the first dorsal almost as high as the second; the soft rays are three or four in the ventral fins; the lateral line runs uninterrupted and distinct from the head to the base of the tail; in the cottoids, the lateral line is remarkably developed, being in some a regular cartilaginous tube with a series of openings communicating by pores of the skin with the surrounding water, leaving no doubt that this line in fishes is intended to supply water to the system.
The common bullhead or sculpin (A. Virginianus, Willoughby) is well known to every boy as a scarecrow among fishes. The body is of a light or greenish brown above, with irregular blotches arranged as four transverse dark brown bars; the abdomen is white, occasionally stained with fuliginous; the dorsals are crossed by dark brown bands, the pectorals light yellow with concentric brown bands, and the ventrals, anal, and caudal yellowish white, also banded. The length is from 10 to 18 inches, of which the head is about one third. There are 10 naked spines on each side, on and about the head, the largest being at the posterior angle of the pre-operculum, and partially covered with a loose membranous sheath; there are also strong scapular and humeral spines, so that it is rather a difficult species to handle; the gape of the mouth is large, and the jaws, pharynx, and palate are armed with numerous sharp, card-like teeth; the caudal fin is even at the end. This species is found from New Brunswick t6 Virginia. Another species of the New England coast is the Greenland bullhead, A. variabilis (Gd.), or A. Groenlandicus (Cuv.); these may be different species, but they are described under one head by Dr. Storer in his "Fishes of Massachusetts," in "Memoirs of the American Academy," vol. v., p. 74. This is darker colored than the common sculpin, with large clay-colored blotches on the top of the head and gill covers, smaller ones on the back and sides, and circular yellow spots on the sides near the abdomen, which is yellow tinged with red, and the throat dull white; the fins are more or less banded and spotted with yellow; the sides are rough from granulated tubercles.
The length is about a foot, of which the head is one fourth; this is armed with spines. These ill-favored sculpins are the favorite food of the Greenlanders, though rarely if ever eaten by us. They are very troublesome in the fishing grounds of the British provinces, as they drive away all desirable fish. The bullheads are voracious, devouring small fish, crabs, echinoderms, mollusks, and almost everything, even decaying matter, that comes in the way. There are several other American species described by Mr. Girard. - The genus coitus (Artedi) has but one small spine at the angle of the preoperculum, and sometimes another smaller, hidden under the skin, and perceptible only to the touch, at the lower margin of the suboperculum; the head is depressed, truncated in front, and broader than high; mouth less deeply cleft than in acanthocottus, but, like that, having teeth on the intermaxillaries, lower maxillaries, and front of the vomer; body smooth, gradually tapering to the tail; second dorsal higher than the first; ventrals with three or four soft rays; lateral line generally interrupted.
The river bullhead ( 0. gracilis, Heck-el) rarely exceeds 3 inches in length, and is of a light green color, with irregular dark brown blotches, largest posteriorly; it is found in the New England states and New York. The G. viscosus (Hald.) is about 4 inches long, and inhabits eastern Pennsylvania and Maryland; the color is yellowish, clouded with black, the first dorsal fin being edged with a narrow line of orange; it receives its name from the sliminess of the skin; it delights in clear spring waters with pebbly bottoms, and lies concealed under stones and stumps, close to the bottom, and, when disturbed, hastens to afresh cover; the eggs are laid in April and May, in round packets about the size of an ounce bullet, under boards and stones; it is supposed that they are watched by the parent, from her having been found under the same cover. Many other species, all small, are described by Mr. Girard as American; others are found in the colder portions of the temperate zone in Europe and Asia, at least six; it is probable that many have been confounded under 0. gobio (Linn.).
Bullhead (Acanthocottus Virginianus).
Greenland Bullhead (Acanthocottus Groenlandicus).
River Bullhead (Cottus gobio).
The family of cottoids appeared on the earth some time during the last period of the cretaceous epoch, the genus cottus appearing in the tertiary. There is a cottoid in the Columbia river, called the prickly bullhead*, for which Mr. Girard has established the genus cottopsis, resembling the marine species in its size, but the fresh-water species in its smooth head; the body is beset with prickles, there is one preopercular spine on each side, and the teeth of the palatine bones are card-like; its length is from 9 to 10 inches; it is the C. asper (Gd.). The name of bullhead is also given to some species of aspidophortis (Lacep.) and hemitripterus (Cuv.), marine genera, extending from the New England coast to the Greenland seas.