THE FLOUNDER FAMILY. 383 



colour at once distinguishing this species, even at so early a 

 stage, from the embryonic dab and other pleuronectids with 

 their bright yellow spots. About 24 hours later, large stellate 

 black chromatophores appear, they and the brown spots having 

 a similar distribution. They are irregularly scattered over the 

 dorsal region, being most numerous just on each side of the 

 middle line and on each lateral line, thus showing a tendency 

 to form two pairs of longitudinal rows, two dorsal and two 

 lateral. 



A day after this, the colours have become pronounced 

 and are more definitely arranged. A distinct row of black 

 stellate spots runs down the mid-dorsal line, and on each side 

 of it is a well-marked row of brownish-yellow spots inter- 

 spersed with a few black ones. 



This arrangement alters very little from now till the eleventh 

 day when the larva emerges from its imprisonment. Plate 

 XVII, fig. 1, shows the newly-hatched larva, which is very 

 small compared with the larval plaice, viz. 2 '3 to 3 mm. in 

 length. Amongst other features it may be noted that no chro- 

 matophores occur upon the yolk-sac ; that the yellowish-brown 

 pigment tends to form a patch of colour just above the vent 

 and another half-way down the tail. A somewhat symmetrical 

 disposition occurs upon the head. The black pigment is inter- 

 mingled with the coloured. Apart from the pigmentation, the 

 larva is perfectly translucent and is very active. 



About the thirteenth day the greater part of the yolk 

 has been absorbed, and the larva has undergone important 

 structural modifications. The lower jaw grows forward and 

 projects in front of the snout, and the marginal fin becomes 

 very broad and deep causing the body to assume the typical 

 pleuronectid shape while it is still perfectly symmetrical. 

 Thus although the pleuronectid larvaa can be readily dis- 

 tinguished at this stage from gadoids by the great depth of 

 body and marginal fin, yet this character is only preparatory to 

 the later changes which result in the peculiar asymmetry of the 

 flat-fish. The general coloration of the little flounder of this 

 age is diagnostic and may be briefly described (Plate XVII, 

 fig. 2). Both the brownish-yellow and the black spots are 



