PENNATULA PHOSPHOKKA. 43 



third section of Fi<». 5 at or, which sliows also that the eg^ after 

 becoininsj completely embedded in tlie mesenterial lilameut has 

 commenced to develope, the stage tigured being that in which it has 

 divided into four equal segments. Other eggs from the same 

 specimen have proceeded considerably further in their development. 



It is difficult in this case to determine whether, on the one hand, 

 the Copepod has been swallowed as food and has escaped digestion so 

 far owing to the thick cuticle covering and protecting its body, the 

 eggs being also destined ultimately to serve as food, and being 

 engulphed by the mesenterial lilameuts for that purpose, but having, 

 owing to their tirni investing membrane, not only escaped digestion, 

 but been enabled to develope up to a certain point ; or, on the other 

 hand, whether we are not dealing with a parasitic animal which has 

 planted itself at the bottom of the stomach, so as to intercept the food 

 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 Entomostracon, which we 

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

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

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

 evidence, to adop: the former view, though fully recognising the possi- 

 bility that the latter one may prove to be correct. 



;/. The Reproductive Organ,s. 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 figiires of the reproductive organs. 



Kollikerf also, though noticing that the sexes are distinct in 

 Peninitula, describes them very briefly, and gives no figures; indeed, 

 no satisfactory account appears to have been published hitherto. 



Externally, there appears 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 FunicuUna. 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 



* Lacaze-Duthiers, " Des Sexes chez les Alcyouaires." Comptes Eeudus de 

 TAcademie Imperiale de Paris, 1865, tome 60, pp. 840 — 843. 



■^ Kolliker : op. cit., p. 125. 



