368 THE FLOUNDER FAMILY. 



body and tail were, on the fifth, tinted gamboge-yellow by 

 transmitted light. Moreover a few appeared on the yolk-sac. 

 Some were hatched on the sixth, and the majority on the seventh 

 day. Cunningham's examples hatched on the seventh or eighth 

 day in April, so that those at St Andrews escaped somewhat 

 earlier, as might have been expected in view of the tempera- 

 ture in July. 



The larval lemon-dab (Plate XV, figs. 6 and 7) has a length 

 of 3'5 to 4mm., and is distinguished by the great length of the 

 yolk-sac in proportion to its depth, and by the peculiar curva- 

 ture of the head from above downward and forward. A con- 

 siderable number of dull gamboge-yellow pigment-grains occur 

 along the edges of the marginal fin both dorsally and ventrally 

 dorsally from the head to the tail, though not quite to the 

 end of the latter ; ventrally from the vent as far as a vertical 

 line from the dorsal grains, and thus the series is short. The 

 head and trunk are faintly yellowish from minute specks of the 

 same pigment, and many occur on the yolk-sac. Under a 

 moderate power of the microscope very finely ramose black 

 pigment is observed in connection with the yellow on various 

 parts of the body. The yellow pigment is not bright, indeed, in 

 the egg it appears a dull greenish yellow. 



On the third day the pigment on the marginal fin is light, 

 yellow, while that of the trunk is dull greenish-yellow, pro- 

 bably from the greater development of black. The yolk has 

 much diminished. The eyes are silvery, and the slender little 

 fishes are active and sensitive. Next day the gills are 

 fairly formed, and the mouth gapes, without any movement 

 of the jaws, while the gullet seems to be open. The breast- 

 fins are large and fan-like, and in swimming vibrate with 

 great rapidity. As in the plaice under such abnormal con- 

 ditions, the head is often directed downward so as to reach 

 the bottom of the vessel. Five dull greenish-yellow spots occur, 

 viz., the patch at the breast-fins, one just in front of the vent, 

 and three in the region behind, yet the species is not readily 

 seen in the water (Plate XV, fig. 8). 



On complete absorption of the yolk (Plate XV, fig. 9) 

 the early post-larval lemon-dab is characterised by great depth 



