REPORT ON THE PENNATULIDA. 195 



supplies captured by the polype, and which has found in the mesen- 

 terial filaments a suitable nidus for the development of its eggs. 



Although the general appearance of the Eutomostracon, which we 

 have been unable to identify, suggests parasitic habits, and although 

 there is no sign of either the animal itself or its eggs undergoing 

 digestion, we are disposed, in the absence of any more definite 

 evidence, to adopt the former view, though fully recognising the possi- 

 bility that the latter one may prove to be correct. 



//. The Reproductive Orunm. Concerning the reproductive organs of 

 Pennatula, we have been able to make some observations of interest, 

 owing to the fact that the two Oban specimens are of opposite sexes. 



Lacaze-Duthiers * was apparently the first to show that in Pennatula 

 the male and female organs are borne on separate colonies. He 

 examined, however, only a very small number of specimens, and 

 merely records the fact that the sexes are distinct, without giving any 

 description or figtires of the reproductive organs. 



KoUikerf also, though noticing that the sexes are distinct in 

 Pennatula, describes tlum very briefly, and gives no figures; indeed, 

 no satisfactory account appears to have been published hitherto. 



Externally, there ajipears to be no definite or constant difference 

 between the two sexes ; a difference in shape between the two Oban 

 specimens has already been alluded to as a possible distinction, but 

 whether it is so or not could only be decided by an examination of a 

 far larger number of specimens than we have had an opportunity of 

 investigating. 



In the female specimen, Figs. 1 and 2, the reproductive 

 organs are closely similar to those of Funiculina. The edges of 

 the six mesenteries which bear higher up the short thick 

 filaments act as ovaries, and the ova appear as individual epithelial 

 cells, which grow rapidly, and are from the start invested by a thin 

 membranous sheath, and later on by a second outer, very thick and 

 strong capsule, formed by the surrounding epithelial cells. During the 

 greater part of their development the ova are attached by short stalks 

 to the edge of the septa, and project freely into the body cavity of the 

 polype. 



When ripe the ova become detached from the stalks and lie freely 

 in the polype cavity. Each ripe ovum is a spherical body about 0-015 

 in. J diameter, consisting of a very dense pigmented outer capsule of 

 great strength and considerable thickness, with its surface marked as 

 in Funiculina by an irregular network of low ridges, and presenting at 

 one spot a very conspicious aperture or micvopijle for admission of the 

 spermatozoa ; within this capsule is a second inner and much thinner 

 membrane, inside which is the ovum itself ; this consists of granular 

 protoplasm imbedded in which, usually close to one side, is a very 



* Lacaze-Duthiors, " Des Sexes chez las Alcyonaires." Coiuptes Rendus de 

 rAcadeiuio Iinperiale de Paris. 1865. Tome GO, pp. 840—813. 



+ KiiUikor : Op. cit., p. 1-25. 



; In the account of Funiculina on p. .'iG, the diameter of the ova is stated by 

 mistake to be 0-001 iu., it sliould be O'Oll in., the thickness of tho capsule 0-0(Ji 

 in., and the size of the germinal vesicle 0-003 by 0-UOJ in. 



