344 HISTORY OF BRITISH ZOOPHYTES. 



I insert also in this place, by the same kind permission, 

 Mr. Busk's account of this zoophyte, new to our British 

 Fauna. 



" In stating the form of the cells in this genus, it is more 

 convenient usually to refer to the back view of them, as I 

 have done in this case. 



"In habit this species bears so close a resemblance to 

 S. scruposa that to the naked eye there is very little differ- 

 ence between them. The branches are a little broader, and 

 perhaps more regularly and more closely disposed. The cells 

 are wider in proportion to their length than in that species, 

 and their sides, especially the upper one, more square 

 and straight. The principal difference in the form of the 

 cell consists in the existence in S. scrupea of a rather deep 

 depression or sinus on the back of the cell, and towards 

 the outer margin, in which sinus is lodged the vibraculum* . 

 This organ is placed considerably more behind the cell than 

 it is in 8. scruposa, and differs somewhat in shape from the 

 same organ in that species. It is wider, flatter, and, as it 

 were, of a spatulate form. The aviculariurn occupies the 

 same position, or nearly so, as in that species, or perhaps is 



* Mr. Busk employs this term to signify the organ furnished with a 

 moveable or vibratile seta, as distinguished from the prehensile avicularia. 



