HALF AN HOUR WITH SPONGES. 



65 



spicules mixed up with and strengthening the horny 

 skeleton. Our readers must remember that the 

 storm-cast specimens are nearly always denuded of 

 the external membrane. In Fig. 27 is given an 

 enlarged illustration of the spicules of this species. 

 Another of our deeper water sponges, not as com- 

 mon, however, as that we have just been endeavour- 

 Fig. 27. 



Spicules of Chalina oculata. 



ing to describe, is the Halichondria ramosa (Fig. 28). 

 It is smaller, firmer, and more compact than the 

 Chalina, although there seems to be little difference 

 else, except in this, that in Chalina there is a fibrous 

 skeleton of keratose, whilst in Halichondria the 

 spicules are interwoven together into a network. 

 When alive, the latter is yellow, orange, flesh-colour, 



