151 



The peculiar characters of the development, the early predo- 

 minance of the yellow pigment on the embryo and on the yolk- 

 sac, and the increase of the black pigment together with a 

 decrease of the yellow colouring during the later stages are already 

 too well known to need a longer description, An egg with the 

 embryo allready advanced is figured in fig. 1. In later stages the 

 oil-globules diminish in size and on hatching they have almost 

 entirely disappeared. The larvae are readily distinguished by the 

 brilliant black pigment on the trunk and the tail and by the 

 intensely black pelvic fins. The breast-fins are quite colourless. 

 A larva of 3,2 mM. leugth of two days after hatching is figured 

 in fig. 2. The black pelvic fins, already carried downward to a 

 ventral position are clearly to be seen, the colourless breast-fin is 

 bidden from view by the black pigment of the trunk. The figure 

 presents a striking resemblance to the larva drawn by RafFaele. 

 Only the black pigment is much more brilliant. 



As to the number of oil-globules in the yolk and the size of 

 the egg the different observers do not agree. The eggs studied by 

 Brook ranged from 1,25 to 1,37 mM. with from 20 to 30 small 

 oil-globules. Those described by Holt presented the same size- 

 limits, but contained only from 11 to 19 small oil-globules. The 

 eggs of the mediterranean were 1,166 mM. and contained only 

 from 4 to 10 oil-globules. Four Trachinus-eggs caught by Ileincke 

 and Ehrenbaum measured from 1,006 to 1,132 mM.. and the 

 yolk contained from 12 to 18 oil-globules. These differences lead 

 the two german authors to doubt whether all the eggs described 

 as belonging ,to Trachinus vipera in reality belong to the same 

 species. And yet I don't think there is good reason to doubt that. 

 The eggs 1 could measure ranged from 1,04 to 1,27 mM. in 

 diameter, and so both the size-limits given by Raffaele and Heincke 

 and Ehrenbaum as well as the smallest eggs measured by Brook 

 and Holt are included, and I have no doubt that prolonged research 

 would give a still higher limit, eggs of 1,24 to 1,27 mM. being 

 by no means rare. 



The smallest number of oil-drops in the yolk I noticed was 6. 



