22, BENNET M. ALLEN 
While the sex-cells of the 9.1 mm. stage are imbedded in the 
mesoderm at the root of the mesentery and always close to the 
median line, they are found in the 11.4 mm. stage to occupy a 
position a short distance on each side of this point. Not only 
have they moved laterally, but they have also protruded into the 
body cavity, accompanied by a few mesoderm cells which are 
intercalated between them, fig. 21, and surround them with a 
thin peritoneal investment as well. 
Amia 15 mm., total length. In this stage the sex-cells extend 
over a distance of 2.70 mm. in the caudad 0.50 mm. of which 
they are very sparse. The sex-glands protrude further into the 
body cavity than in the preceding stage, and the ligament of 
attachment becomes narrower. The genital ridge is very much 
lower in the gaps between sex-cells than it is in the sex-cell 
regions. In spite of the fact that it may be very low for quite 
a distance, it is continuous throughout. The genital ridges 
diverge quite widely at their cranial ends, approaching the median 
line at a point .4 mm. caudad to their point of commencement. 
The sex-cells have almost uniformly used up their contained 
yolk material, although a few scattered ones are still closely 
packed full of them. The sex-cells in specimen A, numbered 28 
on the right side and 49 on the left, the total number being 77. 
The number of sex-cells in specimen B was 38 on the right side 
and 45 on the left, the total being 83. 
Amia 16 mm. long. In two 16 mm. larvae, conditions very 
similar to those of the 15 mm. stage were found. None of the 
sex-cells contained yolk material in a sufficiently large amount 
to be clearly recognizable. The striking thing about these two 
specimens is the very small number of sex-cells present, 33 in one 
case and 39 in another. There is no indication of degeneration 
or of a failure to migrate to the proper positions.. The case 
seems to be similar to one cited in Chrysemys, both being due to 
individual variation. 
These two specimens were taken from the same brood and no 
doubt had the same parentage. Another 16 mm. specimen taken 
from a different brood showed 99 sex-cells, a number not 
very far below the maximum. From this fact, and from the 
