SPONGES. n; | 



sub-dermal reticulation, with rounded meshes averaging about 0*5 millim. in diameter, 

 separated by fibres of about the same diameter (more or less). Over this lies a true 

 dermal reticulation composed mostly of loosely scattered spicules (sometimes aogre 

 gated in slender fibres) lying tangentially in the pore-bearing dermal membrane. 



Spicules. (I.) Tylostyli (Plate XI., fig. 6, a) ; slightly curved, rather stout; with 

 well developed oval heads narrower than the middle of the shaft, from which they 

 are separated by a well marked constriction ; gradually or rather abruptly sharp 

 pointed at the apex. Size about 0'49 millim. by 0-01 G millim. 



(2.) Large palmate anisochelse of the ordinary form (Plate XL, fig. (J, b, c), 

 measuring about G"06 millim. by 0-024 millim. Very numerous, mostly in groups 

 which look like disorganised rosettes ; found chiefly just beneath the surface. In the 

 dermal membrane numerous small palmate isochelse occur scattered singly ; these are 

 about - 012 millim. long and are probably young forms. 



(3.) Sigmata (Plate XL, fig. G, d) ; slender, C-shaped and contort, up to about 

 0"036 millim. long; numerous. 



(4.) Trichodragmata (Plate XL, fig. G, e) ; short, compact ; about CH)2 millim. by 

 0-006 millim. Very abundant. 



This species is very closely related to Espcrella fusca, Ridley and Dendy (1), 

 obtained by the "Challenger*' off Bahia ; it differs, however, in the more strongly 

 developed main skeleton and consequently greater hardness of texture, and in the 

 sharply pointed character of the tylostyles ; possibly also in colour. 



R.N. 240 (Ceylon seas). 



Esperella tenuispiculata. n. sp. 



Sponge irregularly massive, with a tendency to grow out into rounded lobes or 

 short, thick branches. Surface very uneven, covered over by a soft dermal membrane. 

 Vents few, small, scattered. Pores scattered (perhaps in irregular groups) in the 

 dermal membrane. Texture (in spirit) soft and spongy, but intensely gritty from the 

 presence of an immense quantity of coarse sand, chiefly in the interior of the sponge. 

 Colour varying from grey to brown. The largest specimen is about 63 millims. long 

 by 36 millims. in greatest breadth. 



The skeleton is to a large extent replaced by the abundant sand-grains, which may 

 he held together in very irregular bands by spongin cement. Between and in 

 association with these we have loose, wispy bands of styli running towards the 

 surface, or simply scattered styli. There is no dermal skeleton. 



Sjtu-nh's. (1.) Tylostyli, very much reduced ; straight, slender; with distinct oval 

 heads, constricted necks and fairly gradually sharp-pointed apices ; size about 

 - 21 millim. by 0'004 millim., but often more slender. 



(2.) Small palmate anisochelee, about 0'02 millim. long; rather scarce but constant. 



(3.) Slender sigmata, C-shaped and contort, about 0"036 millim. from bend to bend : 

 sometimes very abundant, 



Y 



