32 T. KOMAI : STUDIES ON TWO ABERRAiNT CTENOPHORES 



features concerning gonads that have been revealed by the works of 

 Krempf and myself. 



All the three species examined by me showed both the male and 

 female gonads. In Abbott's species, C tvilleyi and C miisukurii, most 

 of the specimens obtained in July and August had male gonad in a 

 mature or nearly mature condition, but, excepting a few individuals of 

 large sizes, those collected during the winter or during the early spring 

 months did not possess the male gonad, and in neither of those two 

 species have I found any mature female gonad — this evidently shows that, 

 the female gonad develops mainly in late summer or in early autumn 

 the same as in C. bocki to be mentioned next. In this species, many 

 of the specimens collected during summer and early autumn months had 

 gonads of both sexes. Especially, individuals obtained between the 

 middle of August and the end of September contained very large egg- 

 cells almost without exception. The eggs seemed to be laid generally 

 before the middle of October. Thus, in the beginning of October, 1919, 

 I observed the species at Misaki, of which most of the individuals con- 

 tained mature eggs and some of them were spawning. One and a half 

 months later, in the latter part of November, when I examined the 

 s pecies again, however, I met with but rarely individuals containing 

 eggs. In short, besides some negligible exceptions, the breeding season 

 of Coeloplana ma)' be said to extend from early summer to early autumn, 

 the gonads developing in the main during summer months and the 

 spawning taking place generally in late summer or in early autumn. 



Coeloplana is hermaphroditic like all ordinary ctenophores. The 

 genital elements develop in the dorsal wall of the eight canals represen- 

 ting the meridional canals of those forms, viz. the subpharyngeal and 

 subtentacular canals (Pi. 2, figs. 2, 4). The eggs {pv) have their origin 

 in continuous tracts throughout the length of those canals, the sperms 

 {te), on the contrary, develop in a certain number of compact mases 

 distinct from one another from the same canals. The relative position 

 of the male and female cells in the same canal is similar to that found 

 in ordinary ctenophores, the eggs situated on the perradial side and the 

 sperms on the interradial side of the wall of the canal. 



Testis. 



The number of testis, i. e., each separate mass of sperms, occurring 

 in one individual varies to some extent with different individuals. In the 

 majority of the cases examined in all the three species, there were met 



