116 PHYLLOSPOKGIA . 



of this tangential network; thus a thin but very tough cortex is formed. 

 The main characters of the supporting-skeleton are the uniformity in thickness 

 of main and connecting-fibres and tlie absence of foreign bodies in the fibres. 

 All the fibres are about 0'04: miUim. thick. The meshes of the supporting- 

 skeleton are about 0-15 millim. wide. Phylhsjwngia velum imitates certain 

 forms of Phicochalma. 



GEOGEAPnicAL DiSTEiBUTioN. — We^t coast of Australia : "Western Australia 

 (Baili/). 



Phyllospongia elegans, n. sp. 



This sponge has the shape of a large, horizontally expanded lameUa, supported 

 by a comparatively long and slender peduncle 30 millim. high, cylindrical, 

 12 millim. thick, and attached to the centre of the circular sponge. The 

 margins of the lamella are much folded, curved upward, and drawn out, 

 to form rounded upturned lobes. The sponge attains a diameter of 200 

 miUim. Prom the upper surface a great number of lobes grow out, which 

 cover the whole of it. These lobes are folded longitudinally, and on an average 

 25 millim. high ; they coalesce here and there, and so an exquisitely flower- 

 shaped structure is produced. The outer surfaces of the 1*8 millim. thick 

 lameHsQ are slightly roughened by the projection of the distal ends of the 

 main fibres. The inner surfaces are deeply grooved (in the skeleton) ; these 

 grooves ramify, and the numerous branch grooves radiate towards the margin. 

 The basal portions of the main central grooves are about 2 millim. wide. The 

 branches decrease rapidly in width as they approach the margin. These 

 grooves appear, as described, in the skeleton only ; in the living sponge they 

 are occupied by lacunose tissue and covered with fine membranes, in which 

 numerous oscula 0'8 millim. wide are situated. The mouths of the exhalant 

 canals appear as conspicuous holes in the floor of the grooves. The sponge is 

 bard, elastic, and not compressible ; the colour is pinkish in the fresh state ; the 

 dry skeleton is light brown. 



The surface-skeleton consists of a thin sand-cortex, which is supported by a 

 network of fibres 0*02 millim. thick, with meshes 0*2 millim. wide. Primary 

 and secondary connecting-fibres cannot be distinguished in the surface-net. 

 The main fibres of the siipiiorting-slceleton are only 0-05 millim. thick, and 

 contain small, axially situated, scattered sand-grains : they are, on an 

 average, 0'3 millim. apart : the connecting-fibres are slightly branched, free 

 from foreign bodies, and 0*016 millim. thick. 



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

 trali;i \ Baily). East coast of Australia (Ramsay). 



