APPENDIX. 375 



4. B.flexilis, n. sp. 



Cells obliquely truncated above with a short spine on the 

 outer angle ; opening large, suboval, with an obtuse angle 

 outwardly; margin slightly thickened, whoUy unarmed. 



Hab. — 0£F Cumberland Islands, 27 fathoms, fine grey 

 mud. 



Of a light grey colour : grows in large loose tufts, com- 

 posed of long forked ascending branches. It is a very 

 peculiar species, and some difficulty has been found in 

 finding it a place. In the opening of the mouth, and the 

 external short spiae, it is a Cellaria ; and in. the colour and 

 want of distinct articulation, it approaches Acamarchis ; 

 whilst in the form of the cell, and their mode of mutual 

 connexion, it is a BiceUaria : it differs from aU other species 

 of that genus, however, in the absence of any long spines, 

 and in general habit. Were it not referred to that genus, 

 it would probably constitute the type of a distinct one. A 

 curious little trident-Uke organ is visible in the narrow part 

 of some cells. 



15. AcAMAKCHis, Lamouroux. 



Char. (B.) — Cells eUiptical,* closely contiguous ; open- 

 ing very large, margin simple, not thickened. Avicularia 

 not always present, hke birds' heads. 



To which may be added, that the species are frequently 

 coloured, red or bluish. 



\. A. neritina. Lamouroux. 



Hab. — Rio de Janiero. Broken Bay, N. S. "Wales. 



This species appears to be one of the most generally 

 distributed of the Polyzoa ; it occurs in nearly every lati- 

 tude in both hemispheres. 



(?) 2. A. tridentata. Krauss. Corall. d. Siidsee, p. 3. 

 fig. 2. 



Hab.— Bass Strait (?) 



• Viewed posteriorly. 



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