BONY FISHES AND GANOIDS. 491 



external form is so familiar, it will not be necessary to say more than that the 

 scales are small and the lateral line distinct. Cod are for the most part in- 

 habitants of comparatively shallow seas of the cooler portions of the Northern 

 Hemisphere, although there are some widely distributed deep-sea forms, and 

 a very few live in fresh water. All the members of the family are edible ; and 

 as they are particularly suitable for salting, their value as a food-supply is 

 very great, although the taste and quality of their flesh is far inferior to that 

 of many other fish. In the typical genus Gadus are included the greater 

 number of the larger and more 

 valuable species, such as the com- 

 mon cod (G. morrhud), the haddock 

 (G. ceglefiiiits), the whiting (G. mer- 

 langus), the pollack (G. pollachius), 

 and the coal-fish (G. virens). In all 

 of these there are three dorsal and 

 two anal fins ; and whereas teeth 

 are developed on the vomerine bones 

 of the palate, the palatines are 

 toothless. Most, although not all, *% 22. COMMON COD. 



have a barbel on the chin. In the 



allied group of the hakes (Merluccius) this barbel is wanting, while the num- 

 ber of dorsal fins is reduced to two, and there is but a single anal ; the pelvic 

 fins being strong, and broad at the base, and teeth being present alike in the 

 jaws and on the vomer. The large fresh- water cod known as the burbot (Lota 

 vulgaris) is found both in Europe and in North America, and has the same 

 number of fins as the hakes, but the body is longer, the head flatter, and the 

 chin bears a barbel. Nearly allied are the marine lings (Molva\ distinguished 

 by having several large teeth on the vomer and in the lower jaw. In the 

 rocklings (Motella) the first dorsal fin merely forms a fringe, partly concealed 

 in a groove ; and there are barbels varying in number with the species to 

 both jaws. Some members of this genus are remarkable on account of their 

 southern habitat, being found in the seas of New Zealand and the Cape. 



Although most familiarly known by the sand-eels, the chief interest in the 

 family Ophidiidce centres round the blind cave-fish from the caves of Cuba. 

 In none of the tribe are the pelvic fins fi>lly developed, and 

 in eome they are wanting ; while there is no distinct first Family 

 dorsal or first anal, and the caudal fin is in most cases nob Ophidiidce. 

 distinct from the other median fins. The two small fresh- 

 water fishes constituting the genus Lucifuga are sufficiently distinguished by 

 the absence of eyes ; but they have a near ally in the marine Brotula, which 

 possesses fully developed visual organs. There are, however, blind deep-sea 

 types, such as Typhlonus. All these retain pelvic fins, which are jugular in 

 position ; but in the typical Ophidium these are replaced by long filaments. 

 Very interesting are the somewhat eel-like small parasitic fishes constituting 

 the genera JSncheliophis and Fierasfer, which frequent the breathing-chambers 

 of sea-cucumbers, the interior of bivalve molluscs, and other safe positions in 

 living animals. They have no pelvic fins, and the vent is situated quite close 

 up to the throat. On the other hand, in the sand-launces, or sand-eels 

 (Ammodytes), while pelvic fins are absent, the position of the vent is normal. 

 These fish which love to bury themselves in the sand have elongated bodies, 

 on which the low dorsal fin extends from a little distance behind the head to 

 the tail, while the anal occupies almost all the hinder half of the lower surface. 



