272 REPORT ON THE PENNATULIDA. • 



started by means of eggs, which, when fertilised, give rise to free 

 swimming embryos, capable of passing from place to place. 



Of the three forms, Funiculina is the most primitive, and was there- 

 fore very properly taken first. Its more primitive nature is shown in the 

 irregular arrangement of the polypes ; in their independent insertion 

 into the rachis ; in the comparatively slight difference between the two 

 kinds of individuals — polypes and zooids — comprising the colony, for 

 these must be supposed to be primitively and fundamentally equiva- 

 lent to one another; and also in the small length of stalk — i.e., of the 

 part of the colony devoid of polypes. A colony being merely an 

 aggregation of similar individuals, whicli, instead of becoming detached 

 and leading isolated and separate lives, remain organically connected 

 together, it is clear that the simplest or most primitive form of colony 

 will be that in which the polypes or individual animals are most 

 completely independent of one another, and in which the differences 

 between one polype and another are the least strongly marked, since 

 all are fundamentally alike, and equivalent to one another. 



Pennaiula is in all these respects a far less primitive form than 

 Funiculina. This is shown by the fusion of the polypes into leaves, 

 clearly a secondary feature that could only have been acquired subse- 

 quently to the habit of forming colonies ; by the very great difference 

 in size between the component polypes of a leaf ; by the great ana- 

 tomical differences between the polypes and zooids ; and by the great 

 relative length of the stalk — i.e., of tlie part of the colony devoted to 

 purely colonial purposes. 



Viroxdarid, though at first sight presenting a closer resemblance to 

 Funiculina than does Pennatula, is in reality the most modified, the 

 least primitive of the three genera, and has, therefore, very properly 

 been considered last in this report. This is especially shown by the 

 restriction of the I'eproductive organs to the imperfectly developed 

 polypes, and the consequent division of the life-history of the polype 

 into two physiologically and anatomically distinct portions — reproduc- 

 tive and nutritive. That the reproductive function should be thrown 

 on the immature instead of the adult individuals is a very remarkable 

 specialisation. 



Again the modified character of Virgularia is shown by the 

 great difference between polypes and zooids ; by the simultaneous 

 instead of the successive develo£)ment of the polypes of each leaf, a 

 point already explained ; and lastly, by the development of the very 

 remarkable system of vessels we have called radial vessels, which, 

 whatever their function may ultimately prove to be, are structures 

 not present in the other two genera, and the possession of which 

 stamps Virgularia as a more highly specialised form than these. 



In concluding our report, which various circumstances have com- 

 bined to render much more lengthy than we had anticipated when 

 commencing it, we desire to record our indebtedness to the members 

 of the Birmingham Natural History Society for the opportunity they 



