A MONOGRAPH OF THE TERTIARY POLYZOA OP VICTORIA. 33 



Family Membraniporid^. 



Zoarium menibrano-calcareous or calcareous, encrusting and expanded and 

 continuous, or in branched series of zooecia, or erect and uni- or bilaniinate, or 

 having the zooecia arranged round an imaginary axis. Zooecia usually (but not 

 invariably) separated by raised margins ; front entirely or partly occupied by a large 

 area, which is wholly membraneous or partially filled in by a thickened lamina ; 

 operculum incomplete. Furnished with avicularia or vibracula. 



The division of this large family into genera is exceedingly difficult, and no 

 satisfactory arrangement has as yet been proposed. In my Catalogue of the 

 Victorian Polyzoa, I adopted the genera Pyripora, Electra, Bathypora, Meni- 

 branipora, Amphiblestrum, Biflustra and Calexchara as being at least convenient. 

 The differences, however, between Membranipora and Biflustra are so slight that I 

 think it is advisable to include them in the one genus. Amphiblestrum, although 

 sometimes difficult to clearly differentiate, has, I think, sufficiently distinctive 

 generic characters, and I, therefore, retain it. I here include also the genera 

 Earcimia, Selenaria and Lunulites. The last two are usually considered as forming 

 a family by themselves, but in essential characters they agree with the other 

 Membraniporidse, and in my opinion should be associated with them. 



In describing the species of this family, the area is the whole front within the 

 margins, the aperture the part entirely open (in living specimens filled in by a thin 

 chitinous membrane and carrying the opercular flap), and the lamina the calcareous 

 or membrano-calcareous layer extending from the margins to the aperture. 



Membranipora, Blainville. 



Zoarium usually encrusting, or sometimes erect and expanded or cylindrical. 

 Zooecia with the area occupying the whole front or with part of the zocecium 

 produced below ; area entirely membranous, so that the aperture corresponds with 

 its whole extent, or slightly filled in by a lamina. 



1. M. radicifera, Hincks. PL IV., figs. 6, 7. 



M. radicifera, Hincks, A.M.N.H., July, 1881; Waters, Q.J.G.S., 1882, p. 262 ; 

 Beania radicifera, McG., P.Z.V., 117. 



Zoarium expanded, attached by numerous radical tubes springing from the 

 backs of the zooecia. Zooecia ovate or elliptical, very deep, with narrow raised 

 margins, separated from each other by round oj)enings which are more distinct 

 behind, the intervening portions being six calcareous tubes uniting each zooecium 

 with six others (as in Busk's genus Diachoris, now merged in Beania) ; anterior 



