NARCOMEDUS.A5 — CUNINA. 



479 



kanowzeff partially bridges the gap in his detailed account of the development of the oogonia 

 and the oocytes and their nuclear phases. (See Zoolog. Centralblatt, Bd. 13, p. 676.) 



The medusa larvawhich develops in the stomach C.proboscidea is attached to the maternal 

 entoderm by means of two of its own ectoderm cells which send out processes into the entoderm 

 of the mother medusa, thus constituting a very primitive placenta. 



The genital cells of the larval medusa, in the stomach of its mother, originate from a 

 single cell in the entoderm of the larva. This cell wanders into the ectoderm of the larva 

 and there it divides to form the genital cells of the developing medusa. 



Stschelkanowzeff's researches may be accepted with more reliance than those of Metschni- 

 koff, for he bases his conclusions upon the study of serial sections, whereas Metschnikoff 

 carried out his observations largely upon macerated material. 



Fig. "IIQ. — Cunina prolijera. A, Side view of mature medusa, with expanded bell-collar. B, One of the sensory-clubs and 

 its otoporpa. C, Bell-margin; t>, velum; p. c, peronial ring-canal system. D, View of tentacle. E, F, G, Suc- 

 cessive stages in growth of first sexual generation in stomach-cavity of swimming medusa. Drawn from life, by the 

 author. Zoological Station, Naples, winter of 1907-08. 



