478 SUPPLEMENT. 



dividuals which do not bear ovaries, at least such as have fallen 

 under my observation have them not." F. W. L. Thomas, R. N. 

 19th Feb. 1847. 



Lepealia punctata, p. 312. In a recent letter from Mr. Peach 

 he tells me that, for the first time, in a very young specimen, he had 

 seen a pair of spines in a central cell, and also the stumps of other 

 spines in more cells. Being very delicate they are destroyed as the 

 Lepralia grows, and when the ovarian vesicles are developed. 



Membranipora membranacea, p. 328. 



When once known, M. membranacea is easily enough recognised 

 again, but I have found it difficult to form a correct idea of the 

 shape of its cells. In a recent and good specimen I found the cells 

 on the margin of the crust to be rhomboidal (or like a coffin), the 

 wall of the posterior part of the cell calcareous and arched, while 

 the anterior and larger part was covered by a flat membrane with a 

 transverse aperture in front for the exit of the polype. The septa 

 were plain, but in older cells there are two short processes on the 

 septa. Before the aperture there is frequently a purse-shaped and 

 calcareous ovary ; and in the space between the cells, on each side of 

 the aperture, there is a prominent and open loop. 



I have stated at p. 316, that Fltislra Peachii of Couch is a state 

 of Lepralia pediostoma, and that it is sometimes so I am still satis- 

 fied, although Flustra Peachii may be also a state of other Lepraliae. 

 Mr. Peach, who thinks it a good and permanent species, has sent me 

 a specimen and drawing of it in its best condition ; and this speci- 

 men I would unhesitatingly refer to Membranipora membranacea, 



POLYZOA HYPOCREPIA. 



Alcyonella stagnorum, p. 391. 



" I have this summer found Alcyonella very plentifully about 

 Norwich, and in two or three cases have found specimens with the 

 tentacula circularly disposed, where, on the same branch, others were 

 of the usual depressed form." Thos. Brightwell, 17th Nov. 1846. 



