BENDY NON-CALCAREOUS SPONGES 125 



The vents are numerous and irregularly scattered on the more exposed parts of 

 the surface. They are mostly minute and each at the summit of a small conical pro- 

 jection, formed by a contracted spicular, membranous margin, but I have seen one 

 expanded up to nearly 2 mm. in diameter. The surface is smooth and appears porous 

 under a pocket lens, but I have not been able to detect the actual inhalant pores. These, 

 however, are no doubt scattered in the thin dermal membrane between the surface- 

 brushes of megascleres. 



The main skeleton is a very irregular, rather close-meshed reticulation of somewhat 

 loose spicular fibre, with a certain number of isolated megascleres scattered between. 

 At the surface this gives place to a velvety pile composed of well denned brushes of 

 megascleres with outwardly directed apices projecting for a short distance beyond the 

 surface. I have detected no spongin. 



Spicules. (1) Styli (tornostrongyla) (Fig. 5a) ; nearly straight, rather abruptly 

 sharp-pointed at one end and rounded off at the other ; often a little crooked ; 

 measuring about 0-266 by 0-007 mm., but often more slender. 



(2) Placochelse (Figs. 5b-5b'"") ; of the typical Guitarra form but with the shaft 

 very abruptly constricted in the middle ; length about 0-041 mm., with greatest breadth 

 of expanded shaft about 0-0143 mm. Numerous smaller forms occur with less sharp 

 constriction in the middle of the shaft ; also numerous very slender forms of various 

 sizes, without fimbrisB or with very feebly developed fimbriee, which I take to be early 

 developmental stages. The placochelaa are abundantly scattered throughout the 

 choanosome. 



So far as I am aware, only three species of Guitarra have hitherto been described ; 

 viz. Guitarra fimbriata Carter [1874], from deep water in the North Atlantic, Guitarra 

 valuta Topsent [1904], from deep water off the Azores, and Guitarra Antarctica Hentschel 

 [1914 ?], from deep water in the Antarctic. Unfortunately, no depth was recorded for 

 our new species, but it was associated with typical shallow water sponges and the 

 depth was probably not more than a few fathoms. 



Guitarra indica differs from all its congeners in the comparatively small size of the 

 placochelao. It seems to come nearest to G. valuta, but differs from that species in the 

 smaller size of the spicules, the presence of the surface pile of megasclere-brushes (in 

 which it agrees with G. fimbriata), and in the abrupt constriction of the shaft of the 

 placochelse. It differs from G. fimbriata and agrees with G. valuta in having torno- 

 strongylote megascleres (styli), and it differs from G. antarctica in having no sigmata. 

 The youngest stages (Fig. 56'") in the development of the placochela), however, resemble 

 sigmata, but they have a peculiar, indefinite, rough outline which seems to indicate 

 immaturity. 



Locality, Register Numbers, &c. II. 4, off Poshetra, 7 January '06 ; IV. 5 a-g, 

 dredged off S.W. coast of Beyt Island. 



