PHORIOSPONGIA. — SIGMATELLA. 195 



cortex 0*8 millim. thick, composed of large, loosely scattered sand-grains, 

 similar to those in the interior. Abundant spicules are observed in the ground- 

 substance ; these are of three kinds : (a) very numerous and uniformly dis- 

 tributed, strongly recurved sigmata, 0-047 millim. long ; (6) rather scarce 

 sigmata, 0-01 millim. long, in the walls of the larger inhalant canals ; and (c) 

 rather scarce and irregularly scattered strongyla, 0*1 milHm. long and 0'003 

 millim. thick. The outermost layer of the superficial cortex is composed of 

 small foreign bodies, intermingled with both kinds of sigmata. 



The subdermal cavities are represented by narrow tangential canals, groups 

 of which converge towards large irregularly spherical cavities, about 1 millim. 

 wide, situated below the cortex at intervals of 2-3 millim. From these local 

 distentions of the subdermal cavities the inhalant canal-stems arise. The 

 latter are about 0*3 millim. wide, provided with annular strictures, and irregu- 

 larly curved, following the centres of the meshes formed by the sand-grain 

 series. The ciliated chambers are comparatively long and slender, measuring 

 on an average 0*08 millim. in length and 0*03 millim. only in width. The 

 exhalant canals join to form proper oscular tubes only in P. lamella, var. oscu- 

 lata, but open direct by numerous vents, about 0'3 millim. wide, in the other 

 variety. 



Phoriospongia lamella, var. panis, nov. 



Lamellar, erect, more or less flabelliform sponges, with a continuous or 

 slightly undulating margin. Without any conspicuous prominent oscula. The 

 exhalant canals open by vents 0*3 millim. wide, which are scattered over both 

 faces of the lamellar sponge. 



Geographical Disteibution. — East coast of Australia : Port Jackson, 

 N. S. W. {Ramsay, Lendenfeld). 



Genus SIGMATELLA, n. gen. 



Spongelidse with a supporting-skeleton composed of a network 

 of very areniferous fibres, with rod-shaped and often sigmata 

 microsclera. 



Sigmatella australis, n. sp. 



(The synonyms will be found in the description of the varieties.) 



Large, tubular, erect sponges, which often attain a height of 200 millim. 

 The whole sponge may consist of a single, irregularly cylindrical, upright tube, as 

 in the case of some specimens of S. a. tuharia ; or more frequently of a bunch 



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