GADID^E. 271 



Order II-ANACANTHINI. 



All the fin rays articulated, the ventral fins, when present, heing jugular or 

 thoracic. Air-bladder, if existing, not having a pervious pneumatic duct. 



The order of spineless fishes, or Anacantliini, has been divided into two groups, 

 in one both sides of the head are symmetrical, in the other not. 



First Group Anacanthini gadoidei. 

 Both sides of the head symmetrical. 



Family I GADID.E, Cuvier. 



PseudobranchisB, when present, glandular and rudimentary. Body more or 

 less elongated. Gill-openings wide : gill-membranes, as a rule, not being attached 

 to the isthmus. From one to three dorsal fins, occupying nearly the entire length 

 of the back, the rays of the last fin being well developed : one or two anal fins : 

 caudal usually free, but sometimes united to the dorsal and anal. Ventrals 

 jugular, consisting of several rays, or should they be reduced to a filament the 

 dorsal fin is divided into two. Scales cycloid, and of moderate or small size. 

 Air-bladder and pyloric appendages usually present. 



Some of the genera, of which representatives have been recognized in this 

 country, have three dorsal and two anal fins, as Gadus : or two dorsals and a 

 single anal, as Merluccius, Phycis, Molva, Lota, and Motella : while in Brosmius 

 there is only one dorsal and one anal fin. 



Geographical distribution. The cod family is composed of surface and littoral 

 forms, those living off our coasts having been found at a depth rarely exceeding 

 a hundred and twenty or hundred and fifty fathoms. These fishes are extended 

 through the Arctic and temperate regions of the northern hemisphere, becoming 

 almost unknown in the tropics, and very rare to the south of the line. 

 Although as a rule it is composed of marine genera, still fresh-water repre- 

 sentatives are not unknown, as the burbot, Lota vulgaris, which would seem to be 

 descended from a marine ancestry, for like its ocean relatives its air-bladder is 

 destitute of ossicles connecting it with the intei'nal ear (see Introduction).* 

 Reliable evidence confirmatory or the reverse of this view, or whether marine 

 residents among the Gadidaa may be detected living in fresh waters, thus becomes 

 desirable. For should a migration from the sea to fresh waters be undertaken 

 without occasioning deleterious results, it would tend towards confirming the 

 possibility of the correctness of the foregoing deduction. I will now quote (with 

 permission) from a communication which I received from Lord Ducie in 

 September, 1881, directly bearing on this question : 



" I have just returned after having spent two months in the Norwegian Fjords, 

 in my steam 'yacht. In Midgulen Lake, 61 43' N. Lat. and 5. 53' E. Long, from 

 Greenwich, I found pollack living in the fresh water. This lake is about five 

 hundred yards from the sea, with w r hich it is connected by a river averaging about 



* Burbot and Air-bladders of Fishes, F. Day, Proceedings Cotteswold Naturalists' Field 

 Club, 187y-8U, vii, pp. 221-242. 



