108 CEYLON PEARL OYSTER REPORT. 



Coppatias reptans, n. sp. -Plate V., fig. 2. 



The single specimen is much elongated, irregularly sub-cylindrical, creeping over 

 and to a slight extent encrusted by calcareous debris. It has apparently lain 

 horizontally. The total length is about 11 centims., and the maximum thickness 

 about 14 millims. One end is much narrower and forms a free digitiform process, 

 strongly curved. The surface is slightly rugose, minutely conulose and minutely 

 and slightly hispid. The colour (in spirit) is dark purplish-grey, paler below and 

 internally. Vents small (mostly minute), numerous, scattered on the upper surface. 

 Inhalant pores abundantly scattered. 



The main skeleton is a very confused reticulation of oxeote megascleres, here and 

 there collected into loose bundles. There is no special dermal layer of tangentially 

 disposed oxea, but the surface is rendered more or less hispid by the projecting points 

 of oxea which lie below it. There is, however, a thin dermal layer of densely crowded 

 asters. 



Spicules. (I.) Oxea (Plate V., fig. 2, a, b, c) slightly curved and gradually and 

 sharply pointed; varying a good deal in diameter; about TO millim. by 0'022 millim. 

 when fully grown. 



(2.) Chiasters (Plate V., fig. 2, (/) ; very minute, with rather numerous, slender, 

 cylindrical rays and little or no distinct centrum ; total diameter about O'OOG millim. 

 (sometimes a little more) ; most abundant at the surface, but also plentiful in the 

 choanosome. 



The ectosome is fairly thick, but is excavated by numerous irregular, spacious 

 sub-dermal cavities, into which the inhalant pores open and from which the inhalant 

 canals of the choanosome take their origin. It is clearly differentiated into two 

 layers : an inner, comparatively thin and densely fibrous layer, with the fibres mostly 

 lying parallel to the surface, and an outer, much thicker layer composed of collenchyma 

 with a considerable admixture of fibrous tissue, but with the fibres running irregularly 

 in all directions. 



It is a noteworthy fact that the fibrous cells of the ectosome contain a large 

 proportion of the pigment to which the sponge owes its dark colour, arranged in them 

 in the form of minute spherical granules. Similar pigment granules also occur in 

 some of the ordinary stellate cells of the collenchyma, of which the fibre-cells are but 

 a slight modification. 



The. outer part of the ectosome also contains immense numbers of large, spherical, 

 darkly staining cells, crowded together in large groups or loosely scattered. Similar 

 cells also occur very abundantly, scattered singly or grouped in dense masses, in the 

 choanosome. They remind one strongly of the symbiotic Algaj of Hexadella and the 

 corresponding cells of Asteropus haeckeli, and are probably of a similar nature. Their 

 immense numbers and their occurrence in such dense masses in both ectosome and 

 choanosome are alone enough to suggest that they are not true constituents of the 

 sponge-tissues. 



