1 86 



sometimes two. Further back over the rectum one occurs on 

 the dorsal side of the bod}^, and another on the ventral side, in 

 the angle formed by the rectum and the caudal region of the 

 body. Another two in corresponding positions, being above 

 and below the body and sending branchings over towards each 

 other, occur further back, between the anus and the extremity 

 of the tail. The oil globule is covered with densely reticulated 

 pigment cells. A few black dots occur irregularly on the 

 body and head region. The three principal patches of yellow 

 colour, viz., on the head, middle and caudal regions, are readily 

 made out by the naked eye in the newly hatched larva, which 

 soon becomes very active, and when a number are crowded 

 together at the side of a jar they bear a striking resemblance in 

 motion and appearance to copepods. It is possible that these 

 yellow pigment spots, characteristic of many pelagic larva^ 

 may be a case of protective mimicry. 



On the second day after hatching the yolk has greatly 

 diminished and the larva has increased in size, as shown in 

 fig. 9, which represents an embryo of about this age, but from 

 a different hatching, and is selected to illustrate differences in 

 arrangement of pigment in detail, and a difference sometimes 

 observed in the position of the oil globule, which is here 

 situated further forward. Further development is in the 

 direction of the formation of the mouth, which is very 

 apparent on the 4th day after hatching. On the 5th day a 

 change has occurred in the head region. The anterior of the 

 dorsal fin ascends somewhat more abruptly from the top of 

 the 'head. This is st'll more marked on the 6th day after 

 hatching (tig. 10). About this time the larva began to die off,, 

 and shortly afterwards only one was left. From the 7th to the 

 9th da)' after hatching a gradual change appeared in the anterior 

 part of the dorsal fin, consisting of an indentation of the 

 margin in the vertical from the centre of the visceral region. 

 No increase in size was observed from the 7th day and the 

 larvae died, apparently for want of suitable nourishment. 



Some changes were noticed in the colouration on the 7th 

 day after hatching. The yellow pigment cells were better 

 defined in outline and position and were more branched. 

 New black pigment patches appeared at the anal opening at 

 its anterior margin (fig. 10) and a black tract between the 

 digestion canal and the body, extending backwards, though 

 much fainter, to half-way between the yellow caudal spot and 

 the end of the tail. 



