238 THE COD FAMILY. 



average diameter of '055 inches, 1'386 mm. (Cunningham 

 1'39 mm.) with no oil-globule (fig. 19, and figs. 24 to 34). 

 It was described and identified by Sars as early as 1864. 

 Ewart and Brook' have closely watched the spawning of this 

 species in tanks. They state that the egg, after discharge from 

 the oviduct, rises very slowly through the midvvater, one example 

 taking four minutes to ascend through li inch of water''. The 

 micropyle is at the lower pole of the egg and fertilization takes 

 place during the ascent of both sexual elements. 



On the eighth or tenth day after fertilization (in April) the 

 embryo hatches'. Three days before hatching, small round 

 black chromatophores make their appearance upon the head 

 and the dorso-lateral regions of the trunk, though as yet quite 

 irregularly disposed : there is no yellow pigment in this species. 

 The mouth is closed, and the vent is placed immediately behind 

 the yolk-sac, and does not extend to the margin of the fin. The 

 day after this the pigment makes its appearance in the eyes 

 and becomes more abundant over the body, the chromatophores 

 assuming a stellate appearance upon the next day. The 

 pigment of the eye then becomes of a bright bronze hue, and 

 the pectorals assume a bluntly lanceolate shape. Their length 

 is about 4 mm. 



The larval cod at first float more or less helplessly in the 

 water, the large yolk-sac being usually uppermost. The pigment 

 (all black) is aggregated into four conspicuous patches, one 

 behind the pectorals, one towards the posterior border of the 

 yolk and two on the tail. These patches or bands of black 

 pigment upon the transparent larvae give them a very odd and 

 characteristic appearance, especially if they are viewed on a 

 white background (fig. 3, p. 31). The aspect of the larval 

 cod soon after hatching is seen in Plate IX, fig. 1, where the 

 stellate black chromatophores arranged in bands are clearly 

 indicated. In the cod, as in the haddock, the pigment never 

 extends to the fins or over the yolk-sac. 



' Ewart and Brook. S. F. B. 3rd Annual Eeport, 1885, p. 54. 

 ^ This is probably exceptionally slow. 



■' Development and Life-history of Food-Fishes. — Mcintosh and Prince, 

 Trans. Boy. Soc. Edin. 1887-88. 



