PLATE 4 
EXPLANATION OF FIGURES 
12 Transverse section of the rudimentary sex-glands of a 24 mm. larva of 
Lepidosteus osseus. > 300. 
13 Transverse section of a sex-gland of a 110 mm. specimen of Lepidosteus 
osseus. X 300. 
14 Part of a transverse section of a 17 mm. larva of Lepidosteus osseus, show- 
ing the reduced vitelline mass. 
15 Detail drawing of a portion of the vitelline mass of the above section. 
X 300. 
16 Transverse section through the region immediately lateral to the pos- 
terior portion of the sub-germinal cavity of a 147 hr. embryo of Amia calva. X 
300. This shows the place of origin of the sex-cells. 
17 Section passing similarly through another specimen of the same stage of 
Amia calva. X 300. 
One sex-cell shown as it is pushing up into the mesoderm. 
18 Transverse section through the hind-gut of a 6 mm. larva of Amia calva. 
x 300. 
19 Transverse section through the hind-gut of a 7 mm. larva of Amia calva. 
x 300. 
