182 HIROSHI OHSHIMA 
Holothuria tubulosa both sexes occur in approximately 
equal numbers. Lo Bianco (19, 1899, p. 476) found that in 
a certain locality males of Phyllophorus urna occur 
much more abundantly than females. I could pay no special 
attention to the sex-ratio of C. echinata during the breeding 
season. But of the specimens collected on April 9, 1914, an 
examination of over 3,000 individuals showed that there were 
1,627 males to 1,596 females, or that the ratio of males per 
1,000 females is 1,019. Both sexes thus occur in almost equal 
numbers. 
5. GENITAL ORGANS. 
In addition to the statements of systematists, such as that 
given by v. Marenzeller (28, 1881, p. 128), I may describe 
some points about the genital organs. 
Genital Tubes.—Both in males and females the genital 
tube consists of an external epithelium, a connective tissue 
layer, and an internal germinal epithelium. The external 
epithelium, which is continuous with the peritoneum, is very 
thick in an inactive stage of the gonads (PI. 8, fig. 2, ep), and 
the connective tissue layer is very thin. I have no positive 
evidence to prove the presence in C. echinata of the muscle 
layer which was found in C. glacialis (Mortensen, 
32, p. 715) and C. laevigata (Ackermann, 1, 1901, 
p- 781). In Pseudocucumis africanus, however, 
T found in the specimens fixed on July 28, 1915, when the 
breeding season was over, rather scattered circular and longitu- 
dinal muscle fibres, a connective tissue layer, and a very high 
external epithelium. Though having the same habit of carrying 
the brood inside the body-cavity, the structure is totally different 
from the peculiar feature found by Clark (7, 1898, pp. 58-9) 
in Synaptula hydriformis. Here he observed a very 
thin external epithelium and scanty connective tissue, which, 
according to that observer, probably break so as to allow the ripe 
egos to escape into the body-cavity. 
Female Gonad.—In a still unripe condition, as was met 
with in the specimens collected on March 27, 1914, the female 
gonad is light purplish grey in colour, with a very thick wall 
