2. SUB-BRANCHIATI.
The fishes of this order are characterised by vertical fins being attached under the pectorals, and immediately suspended to the shoulder bone. Exclusively marine fishes, they inhabit every region of the globe. The order comprehends three families:—I. Discobolidæ; II. Pleuronectidæ, or flat fishes; III. the Gadidæ.
I. DISCOBOLIDÆ.
The family of Discobolidæ consists of a small number of species characterised by their ventral fins being discoform, as in the sea-snails (Liparis), in which the lengthened mucous body is without scales, but with one long dorsal fin; the pectoral and ventrals forming one disk, as in Fig. 367, or the Suckers (Lepidogaster), where the pectorals and ventrals form two disks.
Fig. 367. The Sea-Snail (Liparis).
In the Lump-fish, Cyclopteris (Fig. 368), the disk formed by the ventrals forms a sort of sucker, by which the fish attaches itself to the rocks; while the Echineis is remarkable for the disk-like sucker with which it is provided.
Fig. 368. The Lump-fish (Cyclopteus).
