70 REPORT ON THE PENNATULIDA. 



genera the reproductive elements, ova or spermatosplieres, are developed 

 within the polypes, in Vir(jularia they are formed independently of the 

 polypes, and in a part of the rachis where the polypes are either 

 altogether absent or at least very immature. 



It will be remembered that in FunicuUna we described and figured 

 the occurrence of ova in the canal system of the rachis (Plate II., Fig. 

 10, t), and left it uncertain how these ova got into canals which, 

 except at the points where they lie, are much too small to admit them. 

 The condition of things in Virnularia renders it not improbable that 

 these ova have originated and been developed in the position in 

 which we find them within the canals. 



All the four Oban specimens in which the lower end of the rachis is 

 perfect, prove on examination to be females, so that we have had no 

 opportunity of investigating the development and relations of the 

 male organs. We regret this the more because the descriptions we 

 possess of these organs are not in all respects satisfactory. 



Young ova in the earlier stages of development are only found at 

 the very bottom of the rachis, or, at any rate, only where the polypes 

 are very immature ; they are also far more abundant in the ventral 

 than the dorsal half of the rachis, if, indeed, they are not confined to 

 the former. Mature ova — i.e., eggs which have reached their full size 

 and become detached from their stalks, are found extending much 

 higher up the rachis, and may occur in the body-cavities of fully- 

 developed polypes. 



If it is borne in mind that each leaf commences its existence at the 

 bottom of the rachis, and is gradually forced upwards by the successive 

 development of new leaves below it, it will be seen that each leaf in 

 the early stages of its existence has fully-developed reproductive organs, 

 but no organs for digestion of food or capture of prey ; and that in the 

 later stages of its life it loses its reproductive organs and develops 

 prehensile and digestive organs. In other words, the two great functions 

 of nutrition and repz-oduction, which are carried on simultaneously in 

 the polypes of Fiiniculiiia and Pennatula, occupy in Virgularia different 

 phases of the life-history of the polypes, and strangely enough the 

 reproductive phase precedes the nutritive ; the polypes develop repro- 

 ductive organs and products while they are yet unable to catch or 

 digest food for themselves, and bj' the time they have acquired organs 

 for these latter purposes the reproductive organs have disappeared. 



In presenting this separation of their life-history into two distinct 

 chapters, as it were, the polypes of Virgularia are less primitive, and 

 more specialised, than those of either of the other genera with which 

 we have been dealing. 



None of the ova that we have examined from the Oban specimens 

 have even commenced to develop, so that we can give no account of 

 the processes of development from our own observations. Dalyell, 

 who kept Virgularia in captivity for some months, informs us * that 



* Sir John Graham Dalyell: " Kara and Remarkable Animals of Scotland," 

 vol. ii., p. 188, 1848. 



