20 REPORT OiN THE PENNATULIDA. 



extend to the bottom of the body-cavity. The remaining six mesen- 

 teries are present, but their free edges below the stomach are not 

 thickened to form mesenterial filaments. 



3. They have no reproductive organs. 



Wliether these distinctions are absolute is, however, very uncertain. 

 In the younger specimens there appears to be a gradual passage from 

 zooids to polypes (Fig. 6), though whether zooids are in all cases 

 destined ultimately to grow up into polj'pes must be left for the present 

 undecided. 



Polymorphism, i.e. the existence of structural differences between 

 individuals living together and fundamentally alike, is very widespread, 

 and attains a high degree of development among Hydrozoa, where we 

 commonly find in a single colony (a) nutritive individuals with mouths 

 and tentacles, which digest food not only for themselves, but for the 

 rest of the colony as well, but are often destitute of means for capturing 

 their prey ; (/;) prehensile individuals, richly provided with thread-cells, 

 capturing the prey and conveying it to the nutritive individuals to be 

 digested, biit themselves destitute of mouth or stomach ; (c) 

 reproductive individuals, often with no mouth or stomach. To these 

 may be added, in many cases, locomotive individuals, whose sole 

 function is to propel the colony through the water; protective indi- 

 viduals, and a variety of other forms. 



Among Actinozoa, on the other hand, though we have an eqiially 

 marked tendency to the formation of colonies by budding, polyinor- 

 phism is exceedingly rare, all the individuals composing the colony 

 being as a rule alike : the most marked examples of polymorphism 

 are shown by the group with which we are now dealing — the 

 Pemiatulida — and even here we only meet with two kinds of individuals, 

 the polypes and the zooids, between which the distinction may be as 

 in Funiculina by no means an absolute one. 



Zoological Position and Affinities. 



The general zoological position of Funiculina is shown in the Table 

 given on page 1 of this Report. The generic characters, as given by 

 Kolliker, our greatest authority on the group, are as follows : — * 



" Genus : Funiculina. Long slender Sea-feather ; stalk short, with 

 no conspicuous dilatations ; polypes inserted directly into rachis ; stem 

 quadrangular. Polypes protruding froin long cups whose margins are 

 produced into eight pointed processes, each of which contains in its 

 interior a prolongation of one of the body compartments surrounding the 

 stomach, and in its walls longitudinal series of long slender calcareous 

 needles which extend a certain distance down the cups and end in a 

 number of oblique and transversely placed needles. Polypes in 

 obliquely placed rows on the dorsal angles and adjoining sides of the 

 rachis : tentacles with no calcareous needles. Zooids of same form as 

 polypes lying on dorsal surface of rachis nearer the middle line than 



Kollikor, op. cit., p. 250. 



