St. Andrews Marine Laboratory. 93 



A second series, fertilized on the same day (15th), arrived 

 at the Laboratory on the 2nd March. These ova had been 

 kept in open vessels on the spot, and conveyed here in the 

 larval condition, viz. about the second day after extrusion. 

 No difference of moment was noticeable. 



On the 3rd March the larval green cod for the most part 

 floated on the water with the yolk-sac uppermost, but were 

 active when interfered with. The liver had increased in size 

 and the urinary vesicle was more evident. The eyes showed 

 minute black pigment-specks and were slightly silvery. The 

 chromatophores were everywhere more iinely ramose, and were 

 dotted over the head and body, being best marked over the 

 pectorals, above the alimentary canal, in the region of the 

 segmental ducts, and on the trunk a short distance behind the 

 yolk-sac. In some, indeed, an approach was made to the 

 pigment-bars of the cod. Occasionally the yolk presents a 

 minute oil-globule on one side, as an abnormality j but, after 

 all, there is no great gulf between the yolk which possesses 

 an oil-globule and that which does not. 



The head of the larval fish on the 5th March stood out 

 more clearly from the diminished yolk, the pigment had in- 

 creased in the eyes, the gall-bladder was present, and the 

 chromatophores were more conspicuously ramified. The 

 pigment on the trunk behind the yolk-sac was sometimes 

 grouped in two bars. The embryonic caudal rays were now 

 longer, a few reaching the margin. The pectoral fin was 

 carried more or less erect. The lateral sense-organs corre- 

 sponded with those in the cod. The larvaj were more active, 

 though still floating with the yolk-sac uppermost. 



On the 7th March the grouping of the pigment behind the 

 yolk-sac was more distinct and all the organs were advanced. 

 The mouth was slightly open and the mandible projected out- 

 ward. The embryonic rays in the caudal region passed further 

 forward in the broad marginal fin. The rectum was still high, 

 and a considerable amount of yolk was present. The deve- 

 lopment was comparatively slow, and though some specimens 

 lived till the loth March, the only changes were the diminu- 

 tion of the yolk and the more general distribution of the 

 black chromatophores over the surface of the body. When 

 viewed from the ventral aspect, however, most showed a 

 somewhat regular arrangement of pigment along the sides. 



The green cod thus closely approaches the cod in its deve- 

 lopment, but the arrangement of the pigment distinguishes it 

 from a very early stage. In the later stages of larval life, 

 however, the one approaches the other. In the postlarval 

 condition, and especially in the youn^ state, the eye of the 



