SPONGES. 101 



D. sceptrellifera), but I cannot identify Professor HEKDMAN'S specimen, from deep 

 water off Galle, with any of these. The richness of the Ceylon seas in species of 

 Discodermia is very remarkable. It is strange that I have not been able to find any 

 oi Mr. CARTER'S species in Professor HERDMAN'S collection, but they are apparently 

 all small forms, which would not be likely to attract the attention of a collector. 

 KN. 234 (Station XLL, 12 miles off Galle, 100 fathoms). 



Aciculites, SCHMIDT. 



Lithistida with monocrepid desmas and rhabdi, the latter forming a special dermal 

 layer. Without microscleres. 



SOLLAS, in his report on the " Challenger " Tetractinellida, places this genus in his 

 family Scleritodermidae in the "Sub-order" Hoplophora, but it seems to me that it 

 would fall more naturally amongst the Azoricidse (in the Sub-order Anoplia of 

 SOLLAS). The fact that some of the rhabdi form a dermal layer can hardly be of 

 sufficient importance to justify us in placing the genus not only in a different family, 

 but even in a different "sub-order" from the Azoricidse, to which it is naturally 

 allied by the form of the desma, the presence of rhabdi, and the absence of 

 microscleres. 



Aciculites orientalis, u. sp. Plate IV., fig. 3. 



The single specimen is massive, compact, cushion-shaped, rather irregular, but with 

 rounded outlines, somewhat flattened above and attached below by a broad base to a 

 mass of calcareous debris. Height about 28 millims. ; greatest breadth, 38 millims. 

 Texture compact and stony, but with a comparatively soft dermal membrane, which, 

 on the upper surface of the sponge, is easily separable from the underlying part. 

 Vents numerous, minute (say about 0'2 millim. in diameter, but varying), scattered 

 over the upper surface.* Pores scattered. Surface, in parts at any rate, slightly 

 corrugated, with narrow, ramifying and meandering canals showing through the 

 dermal membrane. Colour in spirit grey, both internally and externally. 



The main skeleton is a very close and compact reticulation of monocrepid desmas, 

 intermingled more or less abundantly with strongyla. In the dermal membrane the 

 strongyla are very abundant and lie for the most part tangentially, forming a more or 

 less continuous dermal skeleton. Beneath the dermal membrane, where the main 

 skeleton is growing, the desmas are found in various stages of development, not as yet 

 connected with one another. 



Spicules. (1.) Monocrepid desmas (Plate IV., fig. 3, a-d). The young spicule (a) 

 is an irregular, elongated rod, with minutely roughened surface, which soon begins to 

 branch. The fully grown spicule (d) usually consists of a strongly curved main axis 

 with branches coming off chiefly on the convex side. These branches proliferate and 



* One much larger opening looks ;is if it might be artificial. 



