STELOSPONGIA, HIKCINIA. 175 



The dry skeleton is exceedingly hard, of a bright brown colour with a golden 

 hue in transmitted light. 



The skeleton consists of longitudinal band-shaped fascicles, radiating from 

 the base to the margin of the cup-shaped sponge. These bands are situated 

 perpendicularly to, and project very much beyond, the external surface ; they 

 are joined by a loose interstitial network. The main fibres in the fascicles are 

 0'16-0'4 millim. thick, on an average O'o millim. apart, and cored with abun- 

 dant spicule-fragments. The transverse fibres in them are on an average 0*16 

 millim. thick, and contain scattered spicule-fragments. The meshes are square, 

 with rounded corners, more or less quadratic, 0*3-0'8 millim. wide ; the 

 smaller they are the more circular do they become. The connecting-fibres are 

 pretty uniformly O'l millim. thick, and curved ; they anastomose to form a 

 network with meshes 1 millim. wide. All fibres show a very distinct stratifi- 

 cation, particularly towards the surface. 



It is possible that Hyatt's Hircinia campana, var. typica *, may be identical 

 with this sponge. The figure is somewhat similar, but there is no description. 



Geogeaphical Distribution. — West coast of Australia : Western Aus- 

 tralia {Baily). 



Genus HIRCINIA. 



Spongidse with a skeleton composed of more or less fascicular 

 main fibres, with meshes 05-3 millim. wide in the interstitial 

 network, and filaments in the ground-substance. 



Hircinia variabilis, F. E. Schulze. 



Hircinia variabilis, P. E. Schulze, " Untersuchungen fiber den Bau und die 

 Entwicklung der Spongien," Zeitschrift fiir wissenschaftliche Zoologie, 

 Band xxxiii. Seite 13 (1879). 



Other synonyms will be found in the description of the variety. 



Sponges of very variable shape. The simplest forms are incrusting. It 

 appears that this shape, which appears common to the young stage of all forms 

 of H. variabilis, is retained by some individuals throughout life. These then 

 appear horizontally expanded, more or less cake-shaped. More often the 

 sponge grows perpendicularly more rapidly than horizontally, and then attains 

 an irregular globose form. Very frequently, however, different parts of the 

 sponge grow with different rapidity, and then irregular rugose, tubercular, or 

 even lobose and digitate forms are produced. But in any case the sponge 



* A. Hyatt. "Eevision of the North American Poriferte. — Part II.," Memoirs of the 

 Boston Society, vol. ii. pi. xv. fig. 12. 



