THE EGG AND DEVELOPMENT OF THE CONGER EEL. 
43 
make out the latter in the thin transparent tail of living specimens. The segments 
represented in the last half of the tail in hg. 10 are therefore not at all reliable. 
Color is late in making its appearance. It is first evident at the end of the tail. 
At 6 p. m. on August 5 some of .the larvae had the following six spots above the 
alimentary canal and along lower margin of the myotonies of the tail: (1) About 
middle of yolk; (2) halfway between this and end of yolk; (3) at end of yolk; (4) in 
front of anus; (5) some distance behind anus; (fi) about the tip of the tail. The 
location of the spots coincides roughly with the moniliform enlargements of the 
abdominal yolk. Other spots are added between these already formed. The rela- 
tive and actual size of the spots differ greatly, but the number is the same in differ- 
ent specimens of the same age. In the oldest larvae the spots represented in fig. 14 
were developed. Aside from those along the lower part 
of the sides there were a few cells on the upper jaw, and 
the scattered cells seen near the tip of the lower jaw as 
early as August 7 (fig. 12) have developed into a well- 
marked spot. The character of the pigment about the 
tail is also noteworthy. In the last stage figured the 
processes of the cells show a tendency to lie parallel to 
the embryonic fin rays. Pigment is formed in the eve 
with its earliest appearance on the body. No color, 
aside from the black pigment spots and the yellowish 
yolk, is seen anywhere about the larva during the time 
the larva: were under observation. 
The fin fold is well developed, reaching from the 
nape around the tail to the yolk-sac. It is much wider along the back and in the 
region of the vent than about the tip of the tail or the ventral line of anterior 
abdomen. No rays had appeared in the oldest larva* observed except about the tail, 
where there appears a distinct radiation. 
tv 
Fig. 11. — Head of larva of the same age 
as that of fig. 10, the mouth normal. 
The enormous development of the posterior half of the fourth ventricle is similar 
to the condition figured by Raffaele. In all but the last stage figured this part of the 
fourth ventricle is a large thin-roofed vesicle, separated from the fin fold in the earlier 
