FISHES — GASTEROSTEIDAE GASTEROSTEUS. 85 



GASTEROSTETJS, Artedi 



Gioi. 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 ; branchiostegals three on either side. First dorsal 

 represented by a scries 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 eovered with transversally elongated plates. Lateral line very obsolete. 



Stn. — Gasteroatetis, Aktedi, Gen. Pise. 1738. — Linn. Syst. Nat. ed. VI, 1748. — Cov. & 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 si^ines more or less numerous, which, added to their small 

 size, render them unfit for the table. The popular ajjjjellation 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 

 innominaia, 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 scutellas, are much less numerous than the others. 



So far, all the species of the western coast of North America which have 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. apeltea and G. occidentalis have, so far at least, not been 

 noticed there. 



