EEPORT ON THE PENNATULIDA. 27 



to the various parts of the body -walls and coenenchym ; and inasmuch 

 as it communicates with the body-cavities of all the polypes it affords a 

 means by which food digested by one polype may be conveyed to 

 others, and so supply them with nutriment. The canal system forms 

 thus the great bond of union between the several individuals of the 

 colony, connecting them together into one organic whole. To what 

 extent the several members of the colony are actually, during life, 

 dependent on one another ; and whether the noi'mal duration of life 

 of the colony is or is not simply that of the oldest polypes, are 

 questions which, though of great interest, we cannot yet answer with any 

 certainty. Concerning the first of these we may, however, note that 

 the smallest zooids have no mouths, and therefore must be absolutely 

 dependent for nutriment on the supply brought to them by the canal 

 system from the polypes and the larger zooids ; while as regards the 

 latter question it is certainly worth noticing that in each of the 

 specimens of FunicuUna taken alive all the polypes and zooids were 

 living and healthy ; no dead or diseased individuals being seen. 



The endoderm of the body-wall is a single layer of rather long 

 columnar cells. In many places these are distinctly ciliated, audit is 

 probable tliat the ciliation really extends over the whole surface. The 

 endoderm, as just noticed, lines the larger canals of the mesoderm, 

 passing into them at the points where they open into the body-cavity ; 

 here also it is ciliated, and it is probable that to these cilia are mainly 

 due the currents which in the living animal undoubtedly pass 

 along these canals. 



Between the mesoderm and endoderm is, as usual among Actinozoa, 

 a system of muscular bands. These are, however, only very feebly 

 developed in the body-wall of Funiculiiia : they consist of— (1) longitu- 

 dinal fibres, whose direction corresponds with the length of the poljpe, 

 and which will be noticed again when the mesenteries are described, 

 and (2) circular fibres, which run transversely round the body -wall : 

 these are but slightly developed; they do not form a continuous sheath 

 as in most Actinozoa, but occur as irregular bauds, usually not extending 

 round more than three-fourths of the circumference of the body-wall. 



The body-wall is thickest below, at its junction with the rachis, and 

 gradually diminishes in thickness as it passes upwards, the alteration 

 affecting the mesoderm only. Owing to the stiffness of this semi- 

 cartilaginous mesoderm the polype body is non-retractile, a point that 

 distinguishes FunicuUna from Favonaria and other allied genera, and 

 one which is clearly correlated with the very feeble development of 

 the muscular system just noticed. 



h. The Calyx. — Tlie calyx with its pointed processes forms a kind of 

 low wall surrounding the bases of the tentacles when these are 

 fully expanded, as in Fig. 7 ; but when the tentacles are retracted, 

 the pointed processes of the calyx are pulled in slightly towards 

 one another, as shown in some of the polypes of Fig. 3, and 

 80 serve to partially close aud protect the entrance to the polype- 



