ORDER III. PLECTOGNATHI.
(Fishes with soldered jaws.)
The skeleton in this Order is partly bony in texture, and partly cartilaginous, presenting a decided approach to the following group, in which the gristly structure wholly prevails. The ribs are present only as mere vestiges: the jaws are formed by the union (or soldering together, if we may so speak,) of the maxillary and inter-maxillary bones, and the arch of the palate is united to the skull, so as to be deprived of independent motion. Hence the mouth in these fishes is small, powerless, and almost motionless. The gill-covers and gill-rays are imperfectly developed; and are concealed under the thick skin, leaving only a small orifice for the escape of the water from the gills. The body is destitute of true scales; the skin is either hard and leathery, and scored into lozenge-shaped divisions, or covered with hard bony spines, or soft and mucous. The form is usually short and thick, sometimes quite destitute of the proportions that we are accustomed to see in other fishes, and, as it were, deformed: the fins are commonly small, and often remarkable for their position or structure; there are no proper ventrals.
The Order before us is very limited in extent as compared with the others; the fishes which compose it, though presenting some curious
