90 CEYLON PEARL OYSTER REPORT. 



in size and sporadic distribution, one can hardly regard their presence as constituting 

 a specific or even varietal distinction. It should be noted, however, that very 

 similar spicules appear to be characteristic of the next species (T. pocvlifera). 



The arrangement of the pores and vents in this sponge is very peculiar and might 

 be thought by some authorities to deserve generic recognition. The former are 

 congregated in more or less deep, cup-shaped pits, guarded by very slender projecting 

 protrisenes and prodisenes ; these pits occur, mostly, at any rate, on the lower parts of 

 the sponge and may slope upwards. The vents (or better, cloacal cavities) are 

 represented by pits containing the openings of excurrent canals. As Sollas has 

 pointed out (15, \i. cxxv), a somewhat similar arrangement is found in his genus 

 Cinachyra, closely related to Tetilla, but that genus is also characterised by the 

 ])resence of a thick cortex containing cortical oxea. In Tetilla hirsuta the cortex is 

 only feebly developed, more or less fibrous, but without special cortical spicules. 



For further specific details I must refer to the original description, to which I may 

 add that the flagellate chambers are apparently eurypylous. 



In the choanosome of R.N. 129 numerous minute and apparently siliceous spherules 

 were observed, up to about 0'004 millim. in diameter. The nature of these bodies 

 will be discussed under the head of Tetilla anomala, in which species they also occur. 



R.N. 129 (deep water off Galle and onwards up West Coast); 177 (lagoon inside 

 the reef, Galle, shallow water); 241 (Ceylon seas). 



Tetilla poculifera, n. sp. Plate I., fig. 6 ; Plate III., fig. 4. 



The type specimen (R.N. 230, Plate I., fig. 6) is somewhat pear-shaped, with the 

 broad end attached to a mass of calcareous organisms (Polyzoa, &c). The apex of 

 the sponge is occupied by a deep cup-shaped cloaca (Plate I., fig. 6, CI.), whose 

 margin is fringed with spicules, and whose floor is a sieve-membrane. The surface of 

 the sponge is uneven, irregularly hispid, and thinly encrusted with sand-grains. 

 Colour (in spirit) yellowish grey. Height of specimen 16 millims., transverse 

 diameter 14 millims. Diameter of cloacal aperture 2 "5 millims. 



The skeleton consists chiefly of bands of large oxea radiating outwards from a 

 central "nucleus"; the ends of these bands commonly project slightly beyond the 

 surface. 



Spicules. (1.) Plagiotrirenes (Plate III., fig. 4, a, b) ; few in number, but 

 evidently proper to the sponge, though, perhaps, not specifically characteristic. A 

 typical example from a boiled-out preparation has a fairly stout shaft, tapering 

 gradually to a hair-like extremity, and about 1'3 millim. long by 0'0185 millim. thick 

 below the cladome ; cladi short and stout, about 0*13 millim. long, with apices fairly 

 sharp and slightly incurved. (I have also seen fragments of two large dichotriames, 

 but it is doubtful whether these are proper to the sponge.) 



(2.) Protrisenes (Plate III., fig. 4, d, d') ; with long, slender shaft, and long, 

 slender, sharp-pointed cladi; conspicuous around the cloacal opening; size variable. 



