SPONGES. 81 



bacillifcra (20) and Stelletta baciltifera, var. robusta (21),* the first and third from 

 Australia and the second from the Mergui Archipelago. SOLLAS places the first in 

 his genus Psammastra, while he places the last in Ecionema, which he distinguishes 

 from Psammastra by the absence of cortex, but Mr. CARTER'S specimens of Stelletta 

 bacillifera, var. robusta, were dry, and it is extremely probable that they possessed 

 a fibrous cortex like that of Ecionema carteri ; the type of Stelletta bacilli/era from 

 the Mergui Archipelago may also have been corticate for anything we know to the 

 contrary, and it is almost certain that CARTER'S three sponges and the Ceylon species 

 belong to the same genus. Moreover, we do not even know whether BOWERBANK'S 

 original type of the genus Ecionema (E. accrviix) was corticate or not, a question 

 which it is impossible to decide without properly prepared sections of good 

 material. 



R.N. 175 (Lagoon inside reef, Galle, shallow water); 188 (Muttuvaratu Paar, Gulf 

 of Manaar, 8 fathoms); 259 (Ceylon seas). 



Ecionema laviniensis, n. sp. Plate III., fig. 2. 



The single specimen is somewhat finger-shaped, but flattened and slightly bifurcate 

 at one (? the upper) end. It measures about 30 millims. in length and 13 millims. in 

 breadth. The greater part of the surface is encrusted with coarse calcareous debris, 

 chiefly Foraminifera and shell-fragments ; where these bodies are absent there is a 

 tendency to be minutely and sparsely hispid. In places there is a minutely porous 

 appearance, easily visible under a pocket lens, due to the presence of small thickly 

 scattered pore-sieves. The vents are probably very minute and scattered I have 

 only observed one. The colour in spirit is pale grey throughout, the texture firm and 

 very compact. 



The main skeleton is a confused interlacement of large oxea, towards the surface 

 disposed more or less nearly at right angles to it and occasionally projecting beyond 

 it. At the surface there is a spicular cortex, about 0'13 millim. thick, composed of 

 microstrongyla with a thin layer of minute chiasters externally. Beneath the 

 spicular cortex lie the cladomes of the comparatively few trisenes, with their shafts 

 penetrating the deeper parts of the sponge at right angles. (It is, perhaps, worth 

 noting that in the deep groove at one end of the sponge, where it is beginning to 

 bifurcate, the spicular cortex is not developed and there are apparently no triaenes, 

 but the large oxea project much further beyond the surface than they do elsewhere.) 

 There are also a few slender anatriasnes and protrigenes (?) with cladomes projecting 

 far beyond the surface. 



Spicules. (1.) Dichotriames (Plate III., fig. 2, a, 6); with stout shaft which 

 typically tapers very gradually to a fine point, but may be blunted ; protocladi short 

 and stout ; deuterocladi about the same length or a little longer or shorter, conical, 



* Vide also SOLLAS, "Challenger" Tetractinellida, p. 197. 



H 



