100 . TREUBIA VOL. Il, 1. 
Fig. 1. Egg in the course of Fig. 2. Egg, three days old, 26 X. 
the second day, 26 X. a outer, ot, otocyst, 
b inner egg-membrane. p.f., pectoral fin. 
The second morning we find the tail growing out, the length of the 
embryo now being about °/, the circumference of the egg. The heart, 
situated on the left side of the embryo, is seen beating. By muscular ’ 
contractions the embryo makes quite vivid movements now and then. 
On the yolk we discover the first indication of little black pigment-cells 
distributed regularly over the surface. 
The third morning these black pigment-spots begin to branch. As a 
consequence of the growing out of the tail the embryo now extends round 
more than 360° of the circumference of the egg. It lies coiled up, not in 
a flat but in a screw-like manner, with the tail at the right side of the 
head (fig. 2). This gets more pronounced still in the course of the day 
and the following night. The continuous median fin fold is evident and 
the rudiment of the pectoral fins may be seen in fig. 2. 
Ry 
m | 50 | 
N A | 
nes RÉ CRETE = 
VA (Aa See eee SE Lor .. 
ae ge ee Css Peers Ae | 
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Fig. 3. Larva, immediately after hatching#26 X. 
g, gut, À, heart, of, otocyst, y, yolk, 
The fourth morning the Jarvae became free. Fig. 3 represents a newly 
hatched larva. It has a length of about 6 mm. Along the whole ventral 
side, also of the tail, it is dotted with finely branched black pigment-cells 
