168 STELOSPONGIA. 



has a wide range. It has been obtained from the West Indies, the South 

 Atlantic, the Indian Ocean, and the Australian Seas. The centre of distri- 

 bution lies in the latter, where some of the varieties are among the most 

 common sponges. 



Stelospongia australis, var. conulata, Hyatt. 



Stelosj)07ic/os levis, A. Hyatt, " Eevision of the North American Poriferae. — 

 Part II.," Memoirs of the Boston Society, vol. ii. p. 530 (^1877). 



Stelospongos levis, var. rotundtis, A. Hyatt, I. c. p. 530. 



Stelospongths levis, H. J. Carter, " Descriptions of Sponges from the Neigh- 

 bourhood of Port Phillip Heads, South Australia," Annals and Magazine 

 of Natural History, ser. 5, vol. xv. p. 303 (1885). 



Pyriform pedunculate sponges, which attain a height of about 150 millim. 

 Specimens 200 millim. high are rare. The sponge is generally erect, radially 

 symmetrical, with a perpendicular axis. Sometimes, however — probably in such 

 cases where the sponge grows on an inclined plane — the lower attenuated 

 portion, which is drawn out to form the peduncle, appears slightly curved. 

 The greatest width, 50-80 millim., is observed just above the middle, about 

 60 millim. below the distal end. The sponge has a regularly circular trans- 

 verse section. The peduncle is about 20 millim. thick, cylindrical, about 30 

 millim. long, and widened above. The surface is covered with pretty blunt 

 conuli, which often terminate in several points, and are somewhat variable in 

 size, 1-2-5 millim. high and 2-4 millim. apart. Hyatt {loc. cif.) distinguishes 

 two varieties according to the size of the conuli ; this distinction cannot, how- 

 ever, be upheld, as the conuJi vary in one and the same individual as much as in 

 Hyatt's varieties. The conuli are always much higher and further apart on the 

 body of the sponge than on the peduncle ; they are connected by slightly promi- 

 nent ridges which surround concave, polygonal, rarely triangular fields. In the 

 skeleton villi or tufts are observed on the surface which support the conuli of 

 the living sponge. There is always one single osculum which is situated 

 terminally on the summit of the sponge ; it is circular, 8-12 millim. wide, and 

 surrounded by a very thin wall, about 8 millim. high, which appears as a tubular 

 outgrowth from the summit of the sponge. This tube is supported by longi- 

 tudinal fascicles of main fibres which appear as a frill round the osculum in 

 the skeleton. Carter's Stelosi')ongus levis sometimes has more than one osculum. 

 Occasionally several such pyriform sponges are partially fused at their bases, 

 and in such cases an osculum is, of course, observed on the summit of each 

 individual of the colony. Such forms are, however, not so frequent in this as 

 in some other varieties. Carter's polyoscular specimens are such colonies. 



This sponge is perhaps the most common in Australian waters, but although 

 hundreds of specimens have passed through my hands, yet I did not find a 



