a General History of the Marine Pohjzoa. 73 



Membranvpora sceletos. Busk. 



Lepralia sceletos, Busk, Quart. J. Micr. Sc. 1858, Zoophytol. pi. xx. 

 fig. 3. 



This curious species was referred by Busk, who described 

 it from Madeiran specimens, to Lepralia of Johnston ; but it 

 presents the essential characters of the genus Membranipora, 

 and must be ranked under it. I at one time supposed that 

 its nearest affinity was with Membraniporella, JSmitt ; but 

 though the spines meet in the centre of the area and inter- 

 digitate, they do not unite so as to form a single piece, nor 

 are they modified into flattened ribs, as in the last-named 

 genus. 



There are usually about six spines on each side of the cell, 

 which are very massive, and bend inward abruptly, meeting 

 and interdigitating more or less in the centre. On each side 

 of the orifice is placed a broad and shield-like process (modi- 

 fied spine) bearing some resemblance to the operculum of the 

 Cellulariidse, which has, no doubt, a protective function. Mr. 

 Busk speaks of " an ascending spine at each lower angle of 

 the aperture;" but this is hardly a correct description of the 

 pedunculate lamina or plate which closes in at each side the 

 entrance to the cell. The ocecium is rounded, smooth, and 

 silvery. 



Family Microporidse. 



Setosella, Hincks. 



Setosella vulnerata, Busk. (PI. IX. fig. 5.) 



This interesting form occurs amongst the Madeiran dredg- 

 ings and in considerable plenty. It has hitherto only been 

 recorded from Shetland and the coast of Norway (Bergen), 

 and has not been noticed at any intermediate station. 



The primary zocecium is very small, with a subtrifoliate 

 aperture, which occupies more than half the area ; that is, it 

 exhibits the Membraniporidan structure. Below the area it 

 is produced and somewhat pointed. 



There is a peculiarity in the vibracular cell which has not, 

 I believe, been noticed. One side of the margin is more ele- 

 vated than the other, and, to some extent, overhangs the area ; 

 and in the centre of the projecting portion there is a minute 

 prominence. This probably marks the point where the base 

 of the seta is articulated. The same structure is shown in 

 Busk's figures of Cupularia, a genus which is nearly allied to 

 Setosella (B. M. Oat. vol. ii. pis. exiv. & cxvi.). Indeed, 

 in any natural system, these two forms must be closely asso- 



