604 COLLECTIONS FROM THE WESTERN INDIAN OCEAN. 



skeleton — primary fibres vertical to surface, about a spicule's length 

 apart, containing 3 to 5 series of spicules ; secondaries at various 

 angles to primaries, spicules 1- or 2-serial. Sarcode rich brown, 

 subtransparcnt. Spicules acerate, slightly curved, tapering to sharp 

 points from about 3 diameters from ends ; size "17 by '0085 millim. 

 It branches once at an angle of about 35°, its total length is 50 

 millim. (2 inches), and it has involved a mass of Polytrema, Nulli- 

 pore, etc., in its course ; the Nullipore bears the specimen which I 

 have provisionally assigned to Chondrilla mixta, Schulze. 



In the character of the skeleton and the size of the spicules this 

 species resembles the British species Isodictya simulans, Bowerbank, 

 and Chalina montagui, Johnston ; but it has not the firm texture of 

 the former, nor the tubular form of the latter, and I have not found 

 any more nearly allied species. In spite of its repent growth I have 

 assigned it to Chalina rather than to Cladoehalina, the proportions 

 of the spicules and the character of the fibre agreeing with those 

 of typical Chalince (Chalinula of Schmidt), and being in my view 

 far superior as diagnostic characters to those taken only from the 

 external habit. 



Hah. ITarie Louise Island, Amirante group, 16-17 fms. 



ACERVOCHALINA, gen. n. 

 See Part I., p. 398, of this Report. 



21. Acervochalina finitima, var. 

 Chalina finitima, Schmidt, Spong. Atl. Geb. p. 33. 



As on the North-Australian margin of the Indian Ocean, so also 

 in its North-western angle this otherwise West-Indian* species 

 seems at home. Two specimens (the one 25 millim., the other 40 

 millim. in extreme diameter) show the essential characters of the 

 species ; the vents, however, unlike those of the Australian speci- 

 mens, are placed on the margins rather than the upper surface of 

 the sponge, and the spicules are slightly thicker than in both the Aus- 

 tralian and W. -Indian forms, viz. "003 millim. as against -0018 in 

 the one and *0025 in the other. 



Hah. Seychelle Islands, 4-12 fms. 



Distribution. See Part I., p. 399, of this Report. 



RENIERIDjE. 



Besides the probably almost cosmopolitan species Tedania digi- 

 tata, I find that several of the representatives of this generalized 

 Family type have quite a European fades, and I have identified two 

 of them (Reniera indistincta and rosea) with British species; but 

 two members of the same genus, now described for the first time, 

 possess external characters of a definiteness and singularity unusual 



* Also British, if Chalina limbata, Bowerbank, is identified with it. 



