380 APPENDIX. 



Hab. — Bass Strait^ 45 fathoms. 



Sometimes small and parasitic, upon Sertularians and 

 Polyzoa — sometimes independent, then of large growth, 

 forming dichotomously divided fronds, with strap- shaped 

 truncate, unequal divisions. 



b. Cells on both sides. {Carhasea, Gray.) 



2. F. denticulata, n. sp. 



Cells much elongated, narrow; sides parallel, ends 

 square ; an upturned spine on each side at the oval end ; 

 sides of cell denticulate, denticles very numerous, small, 

 acute. Avicularia irregularly distributed on the surface of 

 the frond. 



Hab. — Bass Strait, 45 fathoms. 



Frond divided into numerous strap-shaped, truncated 

 segments, of various widths ; it attains a height of several 

 inches. In habit it is very like some forms of F. iruncata, 

 and there is a Mediterranean species (undescribed ?) in 

 which the cells are denticulate, much in the same way as 

 in the present species, but otherwise quite distinct. 



18. Retepora, Lamarck, 



Char. (B.) — Polyzoarium foliaceous, calcareous, or horny, 

 reticulate; cells only on one side. 



1. R. cornea, n. sp. 



R, amhlgua ? Lamarck. 



Cells oval, not very regularly arranged, in a continuous, 

 foliaceous, subcircular frond ; reticulated with oval spaces, 

 not as wide as the interspaces. Ovicells large, galeriform, 

 immersed, smooth. 



Hab. — Off Cumberland Islands, 2/ fathoms, fine grey 

 mud. 



This remarkable species is so completely a Retepore in 

 construction, that it seems impossible to separate it from 

 that genus, merely from the circumstance that its compo - 

 sition is more horny than calcareous. The frond is more 

 or less orbicular, or rather is composed of more or less 



