NOTES ON COELO PLANA BOCK1 n. sp. 



577 



Another striking distinctive feature of C. bocki consists in the 

 peculiar structure of the polar plates. These are provided at their 

 peripheral margin with 2-5 lobe-like processes, which somewhat remind 

 one of those occurring in the same organ of Ctenoßlana* In large 

 specimens of C. bocki, the occurrence of the processes is nearly constant, 

 though in the smaller ones they may be merely indicated or even 

 altogether absent. In both C . willeyi and C. mitsitkurii, the lobation 

 of polar plates is unknown to me even in largest individuals. 



What is of greatest interest is the fact that a number of C. bocki, 

 as they adhered on the host, were found to overlie a cluster of eg^s 

 which lay in direct contact with the ventral body-surfacj. The eggs 

 contained embryos in varions developmental stages. It was possible to 

 rear up the embryos to an advanced stage in the aquarium. So that, 

 the development of this interesting animal could be followed to a fairly 

 satisfactory measure. 



Genital Organs. — The Coelo plana is hermaphroditic. The gonads 

 develop in the dorsal epithelial wall of certain canals, eight in number 

 and which represent the meridional gastrovascular canals of pelagic 

 ctenophores. The female gonad arises along the entire length of each 

 of these canals as a linear tract of egg cells, exactly as in the ordinary 

 ctenophore. The male gonad, on the other hand, occurs as separate 

 compact masses of sperm-cells along the same canals, there being 4 or 

 5 such masses to each- subtentacuiar, and about 2 of same to each 

 subpharyngeal, canal. Each sperm-cell mass or testis is provided with 

 a duct which opens on the dorsal surface of body and without doubt 

 serves for leading out the spermatozoa. A corresponding duct is entirely 

 wanting to the ovaries, the eggs apparently falling into the lumen of 

 the gastrovascular canals to be subsequently ejected through the mouth. 

 Along and close above each ovarial tract, the dorsal body surface 

 forms a series of deep invaginations which are narrowly tubular in the 



* Korotneff, A. (1886). Ucber Cteiwplana kowalcvski. Z. w. Z. Bd. 43, p. 242. 

 Willey, A. (1896). On Cteiwplana. Q. J. M. S. Vol. 39, p. 324. 



