10 
ovaries, which contain up to 100 fi large oocytes, full of yolk- 
matter, are also located toward the center of the pharenchyma. 
Being so close to the intestinal branches, the ventral parts of these 
ovaries, which contain the largest oocytes, have the hest location 
for nourishment. The reason for the faet that all the larger oocytes 
are, without exception, located in the ventral part of the ovary, is 
of course, its proximity to the intestinal caeca, which constitute 
the source of nutritive supply. Thus, in the ovary of Ceratoplana, 
the germinative zone is always dorsally situated, and, consequently, 
always in the zone above the intestinal caeca. 
The above statements show that, in principle, the grouping of 
the genital giands in Ceratoplana is the usual one oceurring in 
Polyclads; i. e., the ovaries lie dorsally, the testes ventrally. The 
large inerease in the size of the ovaries during maturity, and the 
growing toward the center of the body, has as a result not only that 
both kinds of genital giands reach one another, but also that the 
ovaries, inereasing in size, finally protrude downwards in between 
the testes. The foundation for a further intermixture of ovaries 
and testes seems thus to be established. 
Male genital apparatus. The seminal capillaries are of a 
very fine calibre. The two large seminal canals communicate with 
each other just in back of the female apparatus (text-fig. 6, sc.). 
In hawaiiensis the communicating seminal canal oceurs more poster- 
iorwards (text-fig. 7 sc.). Slightly coiling dorso-ventrally, the 
seminal canals continue frontwards toward the region of the mouth, 
which they slightly pass by. Coiling more and more, and inereas¬ 
ing in width, they turn off in a caudal direction and later on run 
doser to the median-line of the animal. Near the male copulatory 
organ the two canals become narrower, and, turning toward the 
median-line, soon join each other as a short duet, vas deferens 
impar, before entering the seminal vecicle. 
The vesicula seminalis (text-fig. 6 vs.) is oblong and has a 
dorso-ventral position. Both in size, as well as in the strength 
and arrangement of the musculature, it shows similarity to that of 
the genus Stylochoplana. The vas deferens opens into the caudo- 
ventral end of the vesicle. The vesicula seminalis tapers into an 
efferent duet with well-developed muscular wall at its upper or distal 
end, and continues as such to the prostate vesicle, which it enters. 
