General History of the Marine Polyzoa. 277 



rib. 0(£cmm terminal, galeate, flattisli in front, surrounded 

 by a thickened line, somewhat elongate, rounded or subacunii- 

 nate above, surface smooth. 



Log. Port Phillip Heads {J. B. Wih-on). 



In this remarkable species there are none of the lateral appen- 

 dages which arc so common amongst the members of the 

 genus Menipea. They are replaced by the large avicularia, 

 which are intercalated between the marginal cells and form a 

 conspicuous line along the whole length of the branch. These 

 are fixed and destitute of a peduncle ; but the conformation of 

 the anterior or mandibular region approaches very closely to 

 that which we have in Bugula^ and we cannot fail to recog- 

 nize in the avicularium of the present species a transition form 

 leading on to the articulated type. The modification of the 

 marginal cells is another interesting peculiarity ; they are 

 very much larger than the rest and support an array of spines 

 of corresponding size. Another character which deserves notice 

 is the marginal rib which edges the zoarium through its 

 entire extent, composed of the tubular fibres, which play so 

 important a part and discharge so many functions in the 

 economy of the Polyzoa ; they are given off from a small 

 swelling placed on the dorsal surface between the marginal 

 zooecia, which probably represents the vibracular or avicu- 

 larian cell of other forms. This rib exists in many Polyzoa 

 belonging to very different families and was employed by 

 Gray as the distinctive character of his genus Fliistramorpha^ 

 a purely artificial group. 



Family Membraniporidse, 



Faeciminaeia, Busk. 



Farciminaria uncinata, n. sp. (PI. VIII. fig. 2.) 



Zoarium dichotomously branched, stems and branches 

 slender, four-sided. Zooecia disposed in four longitudinal 

 series, elongate, rounded at the top, widest above and nar- 

 rowing gradually towards the base ; margin thin, not much 

 raised, usually a small acuminate spine on each side above ; 

 front wall membranous, semitransparent, more or less covered 

 with minute disks, strongly lined transversely just below the 

 orifice, which is at the very top of the area ; on each side, 

 immediately within the margin and extending for some way 

 down the cell, a hollow structure, sac-like in form, sup- 

 porting towards its upper extremity a strongly pointed uncinate 

 process (or spine) which projects at the side of the oral valve. 

 Owcium very large and prominent, covering about half 

 of the cell, rounded above, flattened in front, and much de- 



