FISHES—GASTEROSTEIDAE-GASTEROSTEUS. 
85 
GASTEROSTEUS, Artedi. 
Gen. Char. —Upper surface of head plane, either smooth or corrugated. Opercular apparatus without any spines. Mouth 
rather small, oblique ; posterior extremity of maxillary not extending as far as a vertical line drawn in advance of the 
anterior rim of the orbit. Minute velvet-like teeth upon the dentaries and premaxillaries ; none on either the vomer or 
the palatines. Gill openings separated beneath by a narrow isthmus ; hranchiostegals three on either side. First dorsal 
represented by a series of isolated spines, varying in number. Belly shielded. Caudal fin sub-truncated or sub-crescentic 
posteriorly. Insertion of ventrals situated opposite the second dorsal spine, therefore abdominal. Body either covered 
with a smooth skin, or partly or totally covered with transversally elongated plates. Lateral line very obsolete. 
Syn. — Gasterosteus, Artedi, Gen. Pise. 1738.— Linn. Syst. Nat. ed. VI, 1748.—Cuv. & Val. Hist. nat. des Poiss. IV, 
1829, 479.— Storer, Synops, 1846, 62. 
The genus Gasterosteus is met with in most of the fresh waters of the cold region of the 
boreal temperate zone of both hemispheres. Although amongst the smallest fishes inhabiting 
the fresh waters, they have not passed unnoticed in any country. They attract the attention of 
the people partly on account of their great multitudes at certain periods, and partly owing to 
the fact of their being provided with spines more or less numerous, which, added to their small 
size, render them unfit for the table. The popular appellation of sticklebacks is most 
characteristic. Besides the dorsal spines, which vary in number from three to eighteen, the 
ventrals are almost exclusively composed, each, of strong and acute spines, which may be 
brought at right angles with the body. Fishes thus armed, though small, have but few 
enemies ; for, it is only necessary for these little creatures to straighten their spines to defy the 
voracity of most of the tyrants of the fresh waters. From the rivers, these fishes extend to the 
brackish estuaries, and even to the genuine salt waters of the bays. In many instances, how¬ 
ever, the species inhabiting the salt waters are different from those occurring in the rivers. 
The inferior surface of the abdomen exhibits a bony shield formed partly by the ossa 
innominata, and partly by the bones of the thoracic arch, the latter diverging from the 
isthmus to the insertion of the ventrals, which are abdominal, so as to leave a middle naked 
area, the former extending from behind the base of the ventrals, posteriorly, in the shape of a 
spear, more or less pointed. 
In some, the body is covered with a perfectly smooth skin ; in others, a series of transversely 
elongated plates may be observed from the thoracic arch to the base of the caudal, diminishing 
in size posteriorly, and reduced to a narrow keel upon the peduncle of the tail. In others still, 
these plates are restricted to the anterior part of the body, from the opercular apparatus to 
about the second dorsal spine. It would be an interesting point to ascertain how far the 
presence or absence of these plates are specific. In many instances no tangible difference is 
observed between specimens entirely smooth and others plated all over, beyond the fact just 
referred to, in which, when plates are present, the peduncle of the tail is keeled, whilst it is 
smooth and plane when the plates are either entirely absent, or exist upon the anterior part of 
the body alone. The habits of each group ought to be carefully investigated, the growth of the 
young watched, and broods kept isolated until they have reached their full development. One 
fact already must appear evident to the most superficial observer : the species with a complete 
series of plates, or scutellae, are much less numerous than the others. 
So far, all the species of the western coast of North America which havn come to our 
knowledge, belong to the type represented by G. biaculeatus, provided with two distinct dorsal 
spines, more or less developed, and a small and inconspicuous one at the anterior margin of the 
second dorsal fin. The types of G. apeltes and G. occidentalis have, so far at least, not been 
noticed there. 
