DENDY NON-CALCAREOUS SPONGES 115 



outer part of the main skeleton. The spicules are very slightly curved, fairly 

 sharply pointed oxea, measuring about 0-078 by 0-004 mm. 



In my Report on Professor Herdman's Ceylon Sponges [1905] I suggested 

 that my Siphonochalina crassifibm should be regarded as a variety of Carter's 

 Siphonochalina (Tubulodigitus) communis, also an Indian Ocean species. Probably 

 we shall ultimately have to unite in one species a considerable number of varieties 

 which exhibit the same characteristic external form, e.g., Tubulodigitus communis 

 Carter [1881], Siphonochalina crassifibra Dendy [1889], Siphonochalina communis 

 var. tenuispiculata Dendy [1905], from the coasts of India and Ceylon ; Patuloscula 

 procumbens Carter [1882, 1885 bis], from Australia and the West Indies ; Siphono- 

 chalina intermedia Ridley and Dendy [1887], from Australia ; Siphonochalina 

 spiculosa Dendy and S. ceratosa Dendy [1890], from the West Indies. In all 

 these localities there seems to be much variation in the relative amounts of 

 spicules and spongin in the skeleton fibres. There is also a good deal of variation 

 in the length and diameter of the tubes, but I do not see how it is feasible to 

 make really satisfactory specific distinctions between the forms mentioned. 



Until, however, it is possible to make a more thorough comparative study of 

 this interesting group of varieties I propose to revert to the specific name " crassi- 

 fibra "for the Indian form in question. 



Previously known Distribution. Gulf of Mannar (Dendy). 



Register Numbers, Localities, <&c. VII., Adatra Reef, 5.12.05 ; XXXIV. 

 5, Channel W. side of S. end of Beyt Island, 3^1 fms., 3.1.06. 



24. Siphonochalina minor n. sp. (Plate II., Fig. 15.) 



The sponge (Fig. 15) consists of a horizontal, subcylindrical or vertically 

 somewhat flattened, branching and anastomosing stolon, from which arise short, 

 slightly branching and sometimes anastomosing, ascending tubes, terminating each 

 in a wide vent. In the best specimen (R.N. XXVI. 4) there is a continuous 

 stolon 53 mm. in length by about 6 mm. in diameter ; the largest tube arising 

 from it is about 35 mm. in height and 10 mm. in average diameter, with a 

 terminal vent about 3-5 mm. in diameter. The stolon itself, though penetrated by 

 smaller canals, does not contain a single, wide, central cavity, as do the tubes 

 that arise from it. The surface is subglabrous, slightly uneven, very minutely 

 granular. The texture is very compressible and resilient, easily torn. The colour 

 in spirit (after formalin) is light brown. 



The main skeleton is a rectangularly meshed network of stout multispicular 

 fibre, the meshes becoming irregularly polygonal in the deeper parts. Primary and 

 secondary fibres are alike and of about the same diameter, 0-034 mm. They are 

 composed of a great number of oxea and a small quantity of spongin, which does 

 not seem to form a continuous investment but is sometimes visible in the angles 



