THORECTA. 145 



This sponge is mentioned by Carter {loc. cit.) "as a variety" of Stelospongus 

 JtabelUfonnis, " which might be termed Slelospongus latus" 



Geogeaphicai, Disteibution. — North coast of Australia : Northern Terri- 

 tory, S. A. (Haacl-e). West coast of Australia : Western Australia (Baily). 

 South coast of Australia : Port Phillip Heads, V. (B. Wilson); Phillip Island, A^. 

 (Boston Sockty Coll.) ; Port Phillip, V. {Lcndenfeld). East coast of Australia : 

 Port Jackson, N. S. W. {Lendenfeld) ; near Sydney, N. S, AV. (Philadelphia 

 Society ColL). 



Thorecta exemplum, var. tertia, Hyatt. 



Spongelia redilinea, xar. erecta., A . Hyatt, " Eevisiou of the North- American 



Poriferao. — Part II.," Memoirs of the Boston Society of Natural Hiatoi'y, 



vol. ii. p. 537 (1877). 

 Stelosponrfos crihriformis, var. stabilis, A. Hyatt, loc. cit. p. 531. 

 Stelospongns crihrocrusta, H. J. Carter, " Supplement to the Descriptions of 



Mr. J. B. Wilson's Australian Sponges," Annals and Magazine of Natural 



History, ser. 5, vol. xviii. p. 371 (1886). 



Pedunculate sponges which sometimes attain a height of 150 millim., but 

 generally are only 100 millim. high. The peduncle is cylindrical, straight or 

 curved, and of the nearly uniform thickness of 4 millim. throughout ; it is 

 generally short, about 20 millim. long, sometimes altogether undistinguishable, 

 and in other cases as much as 200 millim, long. The body of the sponge 

 itself appears massive, conical, irregular, widening above ; it attains a largest 

 horizontal transverse diameter of 50 millim. 



The surface is in large specimens generally covered with a network of bi'oad 

 and high ridges, the interstices between which appear as polygonal or roundish 

 pits, sometimes as much as 12 millim. deep. The oscula are confined to the 

 upper surface. In smaller specimens generally a number of vents, 1-2 millim. 

 wide, are observed, situated in irregular rows on the summits of low sharp 

 ridges on the upper surface. Each osculum is slightly prominent. In large 

 specimens there is generally one large osculum in the middle, which measures 

 10-15 millim. in diameter, and a number of scattered small oscula round it. 

 The latter are not visible in dry specimens destitute of the sand-cortex. The 

 surface is covered with a cortex 1 millim. thick, composed of sand-grains. This 

 cortex is perforated by circular holes 0*7 millim. wide, which are 0-4-1 millinu 

 apart. 



The sheleton consists of slightly knotty main fibres, 0*007 millim. thick, 

 which are about 1 millim. apart and joined by connecting-fibres 0*04-0'035 

 millim. thick. The main fibres are cored with an axial string of pretty large 

 sand-grains and spicule-fragments. The connecting-fibres are straight or 

 curved ; some of theui appear simple and unbranched, joining adjacent main 



I. 



