362 APPENDIX. 



there is a spine, usually of diminutive size, on one side and 

 a very large aviculaiium on the other, and sometimes (but 

 rarely) an avicularium of more moderate size on both sides. 

 But the character of the species by which it is more par- 

 ticularly distinguished consists in the presence on a great 

 many cells, in one part or other of the polyzoary, of the 

 two large and strong spiaes projecting backwards. This 

 retrocession of the spiaes is alone a sufficient character to 

 distinguish the present species from the South African 

 form above alluded to (C taurina, B.) And the length 

 and lateral position of the vittae would distinguish the 

 unarmed cells from those of C. elegans. 



12. C. umbonata, n. sp. 



Cells more or less pyriform, alate, narrow below, bulg- 

 ing or ventricose upwards. Avicularia large and strong. 

 Vittae strap-shaped, anterior, extending from the level of 

 the mouth to the bottom of the cell, with elevated acumi- 

 nate papillae or short spines. A broad compressed project- 

 ing process on the middle of the back. 



Hab. — Bass Strait, 45 fathoms. 



The cells in this species are small, inflated or ventricose, 

 and as it were sub-globular above, becoming much at- 

 tenuated below — but the cavity of the cell does not appear 

 to extend into this contracted portion, in which is con- 

 tained the connecting tube strengthened by calcareous 

 matter — the inferior continuation of the lateral alae, which 

 descend from the base of the avicularium. Owing to the 

 large size of the avicularia, the upper part of the cell is 

 much widened, and the whole acquires somewhat of a 

 triangular form, and has a pecuhar rugose aspect, derived, 

 in part also, from the large size and elevation of the 

 acuminated papOlse, not only of the vittae but on the 

 surface of the cell itself. The central umbo or crest pos- 

 teriorly is a marked feature. 



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