Zoology.-] NATURAL HISTORY OF VICTORIA. [Polyzoa. 



it arises — the mouths of the geminate pair being directed towards 

 each other. The form and arrangement of the avicularia present a 

 very marked feature. On all the cells there is a small avicularium 

 with a sharp-pointed mandible, lodged in the edge of one or both 

 lateral processes ; while in many cells this position is occupied, on 

 one side, by an avicularium of enormous size, frequently nearly 

 equalling the cell in length. These large avicularia, when present, 

 are situated on that side of the cell towards which the mouth 

 inclines. 



The ovicell is of large size, and surmounted by an avicularium 

 sessile on a thick calcareous process. Encircling and forming the 

 upper rim of the mouth is a large semilunar plate on each side, the 

 two being united together in the mesian line. 



Of the two varieties the first is very common, the second of 

 much rarer occurrence. 



Explanation of Figures. 



Plate 24. — Fig. 2, natural size. Fig. 2a, front view of ordinary single and double cells, 

 magnified. Fig. 2b, front view of a cell with an ovicell, magnified. Fig. 2c, back view of 

 ovicell, also single and double cells, magnified. 



Plate 24, Fig. 3. 

 CATENICELLA VENTRICOSA (Busk). 



Description. — Cells ovate. Fenestra 7, pyriform or with a line from the pointed 

 inner extremity. Lower lip entire, notched, or with a small suboral foramen. 

 Lateral processes of moderate size, the upper division generally pointed upwards. 

 Back of cell smooth. 



Reference.— Busk, Voy. Ratt., i., 357 ; Cat. Mar. Pol. Brit. Mus., t. 2, f. 1, 2; 

 t. 3, f. 1-5. 



Forms large, dense, brownish tufts, 3 or 4 inches high, and is 

 of common occurrence. It is readily distinguished by the number 

 and arrangement of the foramina, and by the smooth back of the 

 cell. 



Explanation of Figures. 



Plate 24.— Fig. 3, natural size. Fig. 3a, front view of a branchlet, magnified. Fig. 3b, 

 back view of a single and double cell, magnified. 



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