SPONGES. 151 



Chalina clathrata, a. sp. Plate X., fig. 3. 



Sponge massively encrusting, the single specimen licing attached to the valve of a 

 Pinna ; clathrous ; with very uneven surfiice proliferating into numerous small, blunt 

 outgrowths. Vents numerous and large (up to about 8 millims. in diameter), scattered 

 singly, each at the end of a short tubular projection and forming the termination of ;i 

 wide cylindrical oscular tube. Surface minutely reticulate. Texture very delicate, 

 soft, compressible, resilient ; colour (after drying) light yellowish-brown, with a tinge 

 of purple. The single specimen measures about 220 millims. in maximum diameter. 



The main skeleton is a sub-rectangularly or irregularly meshed network of very 

 pale-coloured horny fibre. The fibre varies greatly in diameter (averaging, say, about 

 0'025 millim.) and contains very few spicules, arranged for the most part uniserially 

 and absent altogether in places. The dermal skeleton is a close, polygonally or 

 rectangularly meshed network of horny fibre cored by uniserially arranged spicules ; 

 the fibres being about 0'0165 millim. in diameter and the meshes about O'l millim. in 

 diameter. 



Spicules. Very slender, usually slightly curved oxea or strongyla, measuring about 

 O'l 12 millim. by 0'002 millim., occurring in and between the fibres and often reduced 

 to vestiges (Plate X., fig. 3). 



With its large prominent vents and deep oscular tubes this species makes an 

 approach to the genus Siphonoc/ialina, while its massive (though clathrous) form 

 recalls RIDLEY'S Acervochalina. 



R.N. 102 (Gulf of Manaar, dry). 



Chalina cymseformis (ESPER ?). 



1 1798-1806, Spongia cymaeformis, ESPKK (6); 1 1870, Spongia cymseformis, EIIJ.KHS (58). 



Sponge shortly stipitate, bushily lamellar or frondose or sub-digitate. Lamella; 

 about 9 millims. thick, with broadly rounded margins. Surface rather uneven, 

 minutely conulose, especially where the dermal membrane has been rubbed on". Vents 

 small (about 2 millims. in diameter), more or less abundantly scattered, chiefly on the 

 inner surfaces of the lamellae. Inhalant pores scattered in the dermal membrane. 

 Texture (in spirit) soft and compressible, but very tough and resilient ; rather woolly. 

 Colour brown. The most typical specimen (R.N. 16) is about 67 millims. high by 

 DO millims. in greatest breadth, with a stalk about 22 millims. high and 18 millims. 

 thick. It bears a very close resemblance to the figure of Chalina palmata, given by 

 RIDLEY and DENDY (1), as well as to ESPER'S figure of his Spongia cyimijormis 

 (Plate G9). 



The main skeleton consists of what, at first sight, look like rather slender, ill-defined, 

 phirispicular fibres running towards the surface at irregular intervals and branching 

 ;is they go, connected by still less well-defined secondary fibres from one to alxmt four 

 spicules broad. No spongin is at first sight visible, but closer examination shows that 

 a very large quantity is really present in the fibres, more or less completely imbedding 



