THE COD FAMILY. 267 



ripe eggs, which are very numerous, being estimated by Earll 

 in one of 23 Ibs., as about 4,000,000. 



The ovary of the coal-fish, like that of the wolf-fish, is pecu- 

 liar in having very thick walls, in which are found circular and 

 longitudinal muscles. Most of the gadoid fishes have ovaries 

 with rather delicate walls. 



The egg of the green cod has a diameter of '0445 inch 

 (1/161 mm.), so that it is, on an average, smaller than that of 

 the cod and comes very near the size of the egg of the whiting ; 

 this and the fact that both are typical gadoid eggs, with no 

 oil-globule, has no doubt caused many of the eggs of the former 

 in their early stages to be classified with those of the latter. 

 Moreover the resemblance of the later stages to those of the 

 cod may partly account for the fact that little has been known 

 till recently concerning the life-history of this species, in spite 

 of its abundance in the adult state upon both the east and the 

 west coasts. At some parts of the latter, indeed, as at Gair- 

 loch, the saithe is caught in immense numbers, and the facts 

 about its early development were gleaned from eggs obtained 

 from that area 1 . 



Eggs fertilized in the middle of February were hatched in 

 about 12 days. They are very transparent and all the organs 

 are clearly discernible throughout the period of incubation. 

 By the 5th or 6th day the embryo has developed black pigment 

 which, viewed ventrally, appears to be arranged in two lateral 

 rows, with a few spots in the median region behind the eyes. 

 The distribution of the chromatophores appears however to vary 

 very much, and in some specimens they are found scattered 

 over the whole surface of the embryo, as in a slightly later 

 stage. On the 8th day the black pigment has increased ; the 

 ear-capsules are ovoid, but afterwards assume the usual spherical 

 shape. A few chromatophores invade the yolk-sac, which has a 

 wavy, oleaginous aspect. In some the oily material collects into 

 a small globule on one side, a variation which shows the very 

 slight distinction really existing between the eggs with oil- 

 globules and those without. On the 9th day the appearance 

 of the egg is seen in Plate III, fig. 8. 



1 W. C. M. 12th S. F. B. Report, p. 218. 



