THE SEA-SCORPION FAMILY. 137 



in May to six days in June or July, the greater mean tem- 

 perature of the latter having the usual effect of hastening the 

 development. 



The yellowish pigment is developed both on the body 

 and the yolk-sac in the egg before hatching, but it appears 

 somewhat later in the embryo in May than in the gadoids 

 and flounders. It consists of pale yellow spots which have 

 a delicate sea-green tinge in certain lights. They are sparsely 

 scattered over the trunk proper, but form a rude line 

 along the back, and an undulating line along the sides, around 

 the eyes and over the yolk-sac. The pigment in the latter is 

 preceded by pale protoplasmic stellate corpuscles. 



The young larva when just hatched (Plate V, fig. 12) is a 

 glassy transparent form with a large yolk-sac, at the posterior 

 border of which is seen the tinted oil-globule, surrounded by a 

 thin layer of protoplasm. It measures about 3"8 mm. The 

 larval fish is conspicuously marked with pigment of two 

 kinds. The dull yellow, sometimes greenish, spots already 

 referred to in the embryo, are scattered over the head, back and 

 abdomen, but are absent from the tip of the tail. The front 

 (dorsal) part of the embryonic fin is picked out, at its edge, by 

 yellow spots, with which are mingled a few black ones, forming 

 a row which invades the fin further behind and meets the 

 pigmentation of the body just in front of the tail. There is a 

 similar but less distinct line on the ventral part of the marginal 

 fin. The pectoral fin has a peculiar arc, of black and yellow 

 stellate spots, which is very striking. Other larval fish described 

 later on have the same banded arrangement upon the pectoral 

 fins. The whole of the black pigment is later in appearance 

 than the yellow, and then to some extent follows the lines of the 

 latter colour on back and fins and is diffusely scattered over 

 the body and yolk-sac in minute black dots. 



Lastly, the pigment, besides being distributed over the 

 surface of the larva, as detailed above, spreads out over the 

 surface of the yolk, which presents scattered yellow and black 

 chromatophores. In this feature the gurnard agrees with the 

 whiting, sole and ling, whilst, on the other hand, it disagrees 

 with the cod, haddock and rockling. The pigment-corpuscles 



