146 



VERTEBRATE ZOOLOGY 



voracious and omnivorous of fishes. It Ijreods far out at sea, and 

 its tiny pelagic eggs are almost inconcc'ivably numerous; as many as 

 nine million eggs have been estimatetl as being laid by a single large 



Fig. 8.^. — daihts inoirliun (Cod), an, anus; </, caiuUil Ihi; ilfl-'l, dorsal fin.s; 

 mx, maxilla; pct.f, pectoral fin; pmx, premaxilla; in'.f, jielvic tin; r/.l and 2, 

 ventral fins. (From Parker and Haswell, after Cuvier.) 



female in one season. Most of us who have been children neetl 

 hardly be reminded of the somewhat unpleasant fact that the 

 liver of tlie Cod is the souice of a, highly nutritious and readily 

 digested oil. J{(^lativcs of the Cod are the Haddock, the Pollock, 

 the Burbot, the Hakc^, and some aberrant and degenerate deep- 

 sea forms. 



The Spiny-Rayed Fishes {AcaiiUiopleriniii). — This tremendous 

 assemblage of modernized fishes reminds one of the passerine 

 birds, because tliey ai'o the most modern of the sub-orders and 

 show a more extensive adaptive radiation than do any of the 

 other groups. The Acanthopterygii comprise no less than thirty- 

 six fanulies including such fannliar tonus as the Bass, Perch, Flounder, 

 Cioby, etc., and a host of less familiar types. 



The conmion Percli is as gootl a tyjK^ to illustrat(^ the sulj-onlcr as 

 any, though it is perhaps thi^ most generalized memljer of the group. 

 Many of the others ti-nd to l)ecome high, compressed, and sliort- 

 bodied, such as the little frcsli-watcr sun-fish. (Jthcr forms that live 

 in the opcui seas have carried out this line of development till the 

 dorso-ventral axis app(>ars to overshadow the primary and the bi- 

 lateral axes, ;is is tlu^ case in some of the Aoiiilhiuriihv, a family 

 which is strikingly exeiuplified by Zaiuiiis (Fig. 86). It is from such 

 tyi)es as this tliat tlu> members of the curious sub-order Pledojnaihi 

 arc thought to have been deri\'ed 



