218 Rev. T. HIncks on the 



and projects at the extremity of the cell instead of standing 

 erect, as it does in A. hirsutum. To the best of my recollec- 

 tion, the apertures are turned slightly outwards; and 1 find, from 

 a note made at the time of its first occurrence, that it resembles 

 an Alecto in habit. 



As it is said to be not uncommon on shells from deep water 

 off the Northumberland coast, we may hope to hear of it again 

 before long. 



Species new to Britain. 



Hippothoa jlageUuvij Manzoni . 



This species, described by Manzoni from the Mediterranean 

 and the Italian Tertiaries, occurs abundantly on our shores 

 and is widely distributed. It has, no doubt, been confounded 

 with H. divaricata^ to which it bears a general resemblance, 

 but from which it is separated by a very important character, 

 in addition to other minor differences. The orifice is subovate, 

 somewhat elongate, rather broader above than below, whereas 

 that of H. divaricata is semicircular, with a straight lower 

 margin and a central notch. The cells are also shorter (less 

 produced below) and in every way smaller ; and the connecting- 

 fibre is very long and slender. 



XXIX. — Note on the Radical Fibres of the Polyzoa. 

 By the Rev. Thomas Hincks, B.A., F.R.S. 



In ^ Nature ' for June 21, 1877, I find a brief notice of a 

 paper on British Polyzoa, by Mr. Peach, presented to the 

 Linnean Society by Mr. Busk, in which the interesting ob- 

 servation is recorded, that '' the tubulous roots " of Scrujyo- 

 ceUaria scruposa are armed with spines, by which it attaches 

 itself to sponges. Much remains to be written of the filamen- 

 tary appendages by which the members of certain genera 

 attach themselves, and their modifications. Mr. Peach's 

 oljservation shows that in S. scruposa^ as in others of its tribe, 

 these organs exist under two forms at least. Commonly they 

 are present as smooth, slender fibres, which adhere to solid 

 bodies by means of a terminal enlargement or disk. It now 

 appears that under certain conditions they take on a different 

 character, are clothed with spines, and act as grapnels by means 

 of which the polyzoon fastens itself to the soft substance of the 

 sponge. I have not noticed these facts in the case of S.. 



