THE COD FAMILY 303 



squeeze the testes in sea-water containing the eggs, he did so, 

 and fertilisation was effected. The soft roes were only 2 to 3 

 inches long in males of good size, and had the form of a frilled 

 riband as in other fish of the cod family. 



The fertilised eggs were sent alive from Lerwick to St. 

 Andrews. They were 13 mm. in diameter (over -^ inch), very 

 nearly as large as those of the cod ; but there was a single 

 large oil globule of a pale red colour. The space between the 

 egg-membrane and the yolk is small. 



The larvae hatched out on the ninth day, and were about 4 mm 

 long (0*5 inch). The oil globule was at the hinder end of the 

 yolk. The black pigment specks were absent from the yolk-sac 

 and fin-membrane as usual in this family, and formed five 

 bands on the body, one on the head, one near the vent, and 

 three on the tail. The coloured pigment is greenish-yellow, 

 and extends on to the yolk-sac and fin-membrane. The larvae 

 lived in the aquarium for a week, at the end of which time only 

 a trace of the yolk remained, and the mouth and jaws were 

 developed. Little change had taken place in the arrangement 

 of the pigment. 



The Sand-eels. 



The sand-eels, although usually placed in a different family, 

 are in many respects similar to the fishes of the cod family. 

 They are distinguished by the following peculiarities : The 

 vent is situated behind the middle of the body, so that the 

 ventral fin is short ; there are no throat fins ; the dorsal fin 

 is single and extends along nearly the whole length of the 

 back ; the tail fin is separate as in the cod-family ; the gill-open- 

 ings are wide, and the lower jaw projects into a spoon-shaped 

 process beyond the upper. This projection of the lower 

 jaw is the instrument by which the fishes burrow into the 

 sand. 



There are two kinds on the British and Irish shores, the 

 larger and the smaller or lesser sand-eel. The larger grows 

 to 12 inches in length, the smaller to 7 inches. They are so 

 much alike that it is very difficult to distinguish one kind from 

 the other, but there seems to be no doubt whatever of their 



