Zoology.-] NATURAL HISTORY OF VICTORIA. [Pohjzoa* 



Plate 60, Fig. 1. 



STEGANOPORELLA MAGNILABRIS (Busk sp.). 



[Genus STEGANOPORELLA (Smitt). (Sub-kingd. Mollusca. Class Polyzoa. Order 

 Infundibulata. Sub-ord. Cheilostomata. Earn. Steganoporellidae.) 



Gen. Char.— Polyzoary expanded, formed of a single layer of cells, or of two united back to 

 back ; cells with calcareous raised margins ; a membranous layer stretched across the front of 

 each cell and separated from the receding calcareous layer, so as to leave a space or chamber 

 between the two ; operculum of outer wall very large, orifice of inner nearly circular.] 



Description. — Polyzoary rig-id, expanded, usually sub-erect; cells quadrate, 

 arranged in linear and alternate series, in a single layer or in two placed back to 

 back ; margins raised, calcareous. A separate membranous layer, # stretched tightly 

 across the front of the cell ; operculum very large, attached on each side to a pro- 

 jecting process of the cell-margin and strengthened by a narrow corneous band. 

 Inner wall a calcareous, punctured lamina, extending forwards and downwards so 

 as to leave a chamber between it and the outer membrane ; it opens by a nearly 

 circular mouth, with projecting margin, behind which a broad square plate, with the 

 sides turned down and united to the lamina, rises to the articulating base of the 

 operculum. 



Reference. — Membranipora magnilabris, Busk, Cat. Mar. Pol. Brit. Mus., 

 p. 62, pi. lxv., fig. 4 zz Steganoporella elegans, Smitt, Floridan Polyzoa, Part ii., 

 p. 15, pi. iv., figs. 96-101. 



• Portland, attached to piles, Mr. Maplestone ; Queenscliff. 



I have only seen dried specimens of this very peculiar species, 

 the structure of which it is to be hoped will ere long be examined 

 in the living state. It seems to be identical with Smitt's S. elegans 

 described from the Gulf of Florida, and no doubt Smitt is correct in 

 considering Busk's Membranipora magnilabris as the membranipora 

 form of the same species. The only difference I can detect in the 

 Australian specimens is that the ordinary cells are more quadrate, 

 and that the large rounded opercula are usually denticulate on 

 the margin. The fossil Eschar a elegans of Milne Edwards is 

 considered by Smitt to be the same species, but I think that 

 determination doubtful, and I have therefore adopted Busk's specific 

 name. 



It is found as a single layer encrusting other objects, or partly 

 free and foliaceous ; at other times it consists of two layers united 



* In different descriptions " zoarium " is used for " polyzoary," " zocecium " is used for " cell," and " ocecium " is used 



instead of " ovicell." 



[43] 



