1 92 TOILERS IN THE SEA. 



is, of course, only the yet spicular and not the solid 

 portion of the tube that is thus inverted ; and the 

 folds thus formed equal in number the tentacles. 

 I have more than once traced these spicular portions 

 up to the very base of the tentacles, where the 

 fusiform spicules end, and the characteristic tentacle 

 and body spicules commence ; these spicules thus 

 forming a series of triangular spaces, the bases of 

 which join on with the hardened edge of the tube, 

 and the apices are situated at the base of each 

 tentacle. The spicules secreted by this portion of 

 the ectodermic layer are of several sorts : first, the 

 warty fusiform spicule, so commonly met with in the 

 Alcyonidae ; these spicules will be found in all stages 

 of growth, and of coalescence ; thus, at the upper 

 portion of the edge of the tube, where it is non- 

 retractile, the calcareous tissue will be found to 

 consist of a series of them, partially joined together, 

 and making a kind of coarse open network, which, 

 on being macerated in caustic potash, does not fall 

 to pieces ; but the retractile portion, on being sub- 

 jected to the same treatment, breaks up into a mass 

 of minute individual spicules. The red colouring 

 matter would appear not to reside in these latter 

 spicules, for those that I have examined are colour- 

 less. A second form of spicule is met with in the 

 retractile portions of the tube, which, I think, might 

 be called 'shuttlecock.' While all the forms of 



