Zoology.-] NATURAL HISTORY OF VICTORIA. IPolyzoa. 



The lateral processes, tlie characteristics of which are largely 

 used in the discruniuation of the species, can, ui many, be seen to 

 consist of three divisions, the middle one being the true avicularian 

 chamber. One or more of the divisions may be largely developed, 

 abortive, or wanting. 



In adcUtion to the species here described, C. amphora and 

 umbonata of Busk, and castanea and Harveyi of Thomson — which 

 have been found in Bass's Straits — are certain to occur on our 

 coasts ; and there is no doubt that a careful search will add several 

 undescribed forms to the list. 



Plate 24, Fig. 2. 

 CATENICELLA PLAGIOSTOMA (Busk). 



Description. — Cells large, wide. Fenestrre 5, very large. Mouth lofty, 

 directed obliquely to one side of the cell. Lateral processes very wide, consisting 

 of an avicularium surmounted by a wide hollow fringe. Avicularia of two sorts, of 

 moderate size, or very much elongated and exceeding half the length of the cell. 

 The back of the cell with a broad longitudinal band, from which proceed, on either 

 side, two narrow bands, one to the avicularian process, the other across the middle 

 of the cell. Ovicell very large. 



Var. a Icevis. — Back of cell destitute of spines. 



Var. (i setigera. — Back of cell with small setose spines in the intervals between 

 the dorsal band and its branches. 



Eefeeence.— Busk, Voy. Ratt., i., 358 j Cat. Mar. Pol. Brit. Mus., t. 5, f. 1, 2. 



Very common, forming handsome, dense, reddish tufts, 3 or 4 

 inches high. 



This is one of the most peculiar species of the genus. The 

 cells are very broad, the front almost entirely occupied by 5 

 fenestrae, the real natm-e of which is here probably better shown 

 than in auy other sj^ecies. The marks on the back of the cell are 

 produced in the same manner as the fenestrse in front, the broad 

 mesial and the narrow diverging bands consisting of the ectoderm 

 which is deficient in the other parts, as it is in the fenestrse in front. 

 The mouth of the cell is very lofty and chrected obliquely to one 

 side, which is constant in all the cells of the same series, and 

 follows the same dhection as that of the gemmate cell from which 



Dec. m. 



[ 17 ] 



