BRITISH ZOOPHYTES. 245 



With a calcareous lamina. 



18. M. Flemingii, Bush. Plate XX. fig. 1. 

 Flustra membranacea {Miill., Fabr.), F. tuberculata 



{O. J., R. Q. C), Ampliiblestrum membranaceum [Gray) . 



Hab. : Common. 



In this species the zooecia are ovate, deep, and ex- 

 tended beneath the apparent surface. The aperture is 

 trifoliate, and each cell has 6 — 8 spines, one of which 

 in the centre of the margin is jointed to a tubular base, 

 and is long, and '' bears no small resemblance to the 

 blade of a scimitar." The appearance of the zoophyte, 

 with its array of sword-like spines guarding each cell, 

 is very curious. In exposed situations these long spines 

 are either not produced or are very soon rubbed off. 



19. M. COENIGERA, Busk. 



Hab.: Shetland {A.M.N.). 



This is a rare species from deep water. The zocBoia 

 are lozenge-shoped, with 6 spines, the lowest pair of 

 which are forked. Large oblong avicularia are dis- 

 tributed amongst the cells. 



20. M. RossELLii, Audouin. 

 Flustra Rossellii {Aud., Savigny). 



Hab.: Shetland {A.M.N.), Isle of Man, Torbay 

 {T. H.), Peterhead (C. W. P.). 



This species forms brown crusts on shells and stones. 

 There are no avicularia, and the zooecia are oval, 

 pointed below with raised and finely beaded margins. 



21 . M. TEiroLiuM, S. Wood. 



Flustra trifolium {8. Wood), Membranipora solida 

 (Pachard), M. sacculata {A. M. N.). 



Hab. : Shetland {A. M. N.), Wick (0. W. P.). 



This species much resembles the preceding. The 



