SIGMATELLA. 203 



Sigmatella corticata, var. flabellum, nov. 



Erect flabelliform sponges with a broad, perfectly continuous free margin. 

 The sponge attains a height of 200 millirn., a breadth of 300 millim., and a 

 thickness of 20-40 millim. It is attached by a narrow base, and the lamella 

 increases in thickness towards the margin, where it appears cut off very 

 abruptly. A special terminal face is thus formed, which extends all along 

 the margin. Near the base it is narrow, but gradually widens above, where it 

 attains a maximum width of 40 millim. The sides of the lamella are rouo-h- 

 ened by low and irregular projections. Sometimes one or a few small lamellse 

 grow up from the same base by the side of the large one, but these never appear 

 to coalesce with the main lamella further up. The surface is, apart from the 

 slight projections on the faces, pretty smooth, somewhat shagreen-like. The 

 oscula are confined to the marginal face, where they are abundant and arranged 

 in several ii'regular rows. They are rather variable in size, from 3-8 millim. 

 wide. In very large specimens a slight depression iu the central line of the 

 marginal face divides the latter into two slightly projecting parts, on. w-hich the 

 oscula are then arranged in two distinct zones. In smaller specimens there 

 is no indication of such a depression, and the oscula are arranged in a single 

 row. Straight cylindrical oscular tubes, which converge towards the base o£ 

 attachment, extend down from the marginal oscula. 



The colour of the living sponge is bright orange-yellow. Dry specimens are 

 very light grey. 



There are, apart from the radial arrangement of the oscular tubes, no 

 distinctive anatomical structures to be recorded in this variety. The external 

 shape it assumes is a very remarkable one, and without precedent in other 

 sponges. 



G-EOGEAPHiCAL Distribution. — South coast of Austraha : Port Pliillip Heads, 

 V. {B. Wilson) ; Port Phillip, V. (Lendenfeld). East coast of Australia : Port 

 Jackson, N. S. W. {Bcmisay, Lendenfeld). 



Sigmatella corticata, var. serrata. 



Dysidea TcirMi (partim), H. J. Carter, " Descriptions of Sponges from the 

 Neighbourhood of Port Phillip Heads, South Australia," Annals and Maga- 

 zine of Natural History, ser. 5, vol. xv. p. 216 (1885). 



Eegularly shaped, erect, flabelliform, lamellar sponges, attached by a narrow 

 base or pedunculate, attaining a height of 170 millim., a breadth of 220 mil- 

 lim., and a thickness of 15 millim. Erom the upper semicircular free margin 

 radially situated digitate processes arise, which are situated at equal intervals, 

 so that the margin attains a regular serrated appearance. These digitate pro- 



