SPONGES. 29 



ing needles. This appears to be the interior lining of the 

 tube, — in fact, the tube itself, around which the spicula 

 are arranged as a loose outer coating, giving firmness to 

 the whole. I could not detect spicula of any other form 

 than the three-rayed stars ; but several of these had one 

 or more of their rays broken short ; for from their compo- 

 sition they are very brittle, as I have often proved in other 

 species. The form of this specimen was so irregular that 

 but a poor idea can be conveyed of it by words; it may, 

 however, be roughly described as an elliptical mass, sending 

 forth from one side several tubes, which divide or branch 

 into others.^^ 



Grantia ciliata 



Is a very minute Sponge, shaped like a bottle ; the neck 

 consisting of a dense fringe of spicula set round the 

 opening so as to form a crown. A stream of water, passing 

 always in the same direction through the aperture, gives 

 the form to these neck-spicula, and it has even been found 

 that if these latter are displaced by accident, so as to bruise 

 and distort the crown, the current will restore them to 

 their natural direction after the specimen has remained for 

 a few days in a vessel of sea-water. 



