140 MEMBRANIPORID^. 



tliey Avere wrought iu silver aud richly chased. In its 

 ordinary condition it has a coarse spongy appearance. It 

 is j)robably the commonest and most abundant of the 

 British Polyzoa. 



The polypides are furnished with the curious interten- 

 tacular organ, which I have described elsewhere"^. The 

 tentacles are liable to many irregularities^ and are often 

 of very different sizes on the same polypide. Very com- 

 monly those on one side are inferior in height to those on 

 the other, and the tentacular bell is obliquely truncate 

 above. The same peculiarity has been noticed by Dr. 

 Farre in Alcyonidium gelat'mosum. 



The palpocils on the back of the tentacles are of consi- 

 derable length. 



Membranipora membranacea, Linnaeus. 

 Plate XVIII. figs. 5, 6. 



Flustra membranacea, Linn. Syst. ed. 12, 1301 : Miiller, Zool. Dan. Prod. 



253 : Ellis cf Sol. Zooph. 18 : Fleming, B. An. 53G : Lamx. 



Pol. corall. flex. 107 : Couch, Corn. Faun. iii. 123, pi. xxi. 



fig. 2 : Johnston, B. Z. ed. 2, 348, pi. Ixvi. figs. 1, 2, 3. 

 Flustra telacea, Lamk. An. b. Vert. ed. 2, ii. 223. 

 Membranipora membranacea, Busk, B.M. Cat. ii. 56, pi. Ixviii. fig. 2 : 



Blainv. Actinol. 447 {not the M. pilosa, forma membranacea 



of Smitt). 

 E.ErT6PLUSTRA TELACEA, D' Orhigmj, Pal. Fran^. Terr. Cret. v. 328. 



Zooecia oblong, disposed in lines, alternate, wdth a stout 

 hollow spine at each angle above ; area occupying the 

 whole of the front of the cell, with a membranous 

 covering; margin smooth. Avicularia none. Closed 

 tubular processes frequently developed from the front 

 wall of the cell. 



Polypide with about 20 very long tentacles. 



* Vide the Introduction to the present work. 



