136 Descriptions of New, 



larium on one side, opposite the lower part of the mouth, 

 with the mandible pointed downwards ; ovicell prominent, 

 thickly perforated by round foramina, and frequently with 

 a thickened rim. 



Port Phillip Heads. 



Hincks (Ann. and Mag. Nat. Hist., August, 1881) has 

 already noticed this variety, which, as he points out, differs 

 only from the normal form in the position and shape of the 

 avicularium. This is situated on one side of the mouth, 

 with the large, spatulate mandible pointed directly down- 

 wards. The size of the mandible varies considerably, being 

 sometimes very broad, and extending the whole length of 

 the ceJl, while in other cases it is much shorter and 

 narrower. Rarely there is another smaller one on the 

 opposite side. There are occasionally small isolated raised 

 patches of more prominent cells, with the avicularia 

 enormously developed. I have not found the normal form 

 of S. reticulata, but Hincks mentions it as occurring in 

 Bass's Straits. 



Mucronella munita, n. sp. Fig. 10. 



Cells oval, indistinct, glassy ; when young deeply areo- 

 lated on the margins, when older smooth or with irregular 

 elevations ; mouth with a projecting denticle on each side, 

 above which is a long, articulated, cylindrical spine, and 

 sometimes one or two others on the upper margin ; mucro 

 squared above ; usually a sessile avicularium, with the man- 

 dible pointed outwards, on one or both sides of the cell; 

 ovicell large, frequently somewhat umbonate in front. 



Port Phillip Heads, Mr. J. B. Wilson. 



I am not sure that this may not prove to be a form of 

 M. coccinea, from which it seems to differ in the smaller size 

 of the cells, the greater development of the mucro, and the 

 form and position of the avicularia. 



Mucronella losvis, n. sp. Fig. 16. 



Cells broadly ovate, arranged in linear series, slightly con- 

 vex, smooth ; mouth rounded above, a broad denticle deep 

 in the lower lip ; peristome raised round the lower lip, pro- 

 duced in the centre into a prominent square or blunt mucro; 

 six stiff, articulated spines on the upper margin ; ovicell 



