IÇI5-J 



Fauna of the Chilka Lake : Sponges. 



43 



slender stems of weeds. In the latter situation it is naturally dwarfed, owing 

 to the limited area to which it is restricted, and its skeleton is so simplified 

 (fig. 9, p. 44) that it resembles that of Topsent' s genus Pvosubevites , which is defined 

 as having all the tylostyles with their heads in contact with the basal membrane and 

 their shafts projecting upwards. At the edges even of sponges of the more vigorous 

 phase a similar arrangement occurs; but, as Dendy l has pointed out, the different 

 genera into which the old genus Suberites have recently been divided are, in some 

 instances, not very clearly separated one from another. In any case, L. aquae- 

 dulcioris is never devoid of horizontal spicules and always, in at least some spicule 

 fibres, some of the spicules are not in contact with the basal membrane. 



ft f? 



A. 



Fig. 8. — Laxosuberites aquae-dulcioris (Annandale). 

 Spicules from type-specimen, x 255. 



A. — Heads of spicules further enlarged. 



The species is abundant on the oyster-shells of the beds near Manikpatna in the 

 outer channel of the Chilka Lake and has also been found, in its less vigorous phase 

 on the stems and leaves of the plant Halophila ovata both in the outer channel and 

 at various places in the neighbourhood of Barkul and Barkuda Id. in the main area. 

 It occurs in water as salt as the Bay of Bengal, of different degrees of salinity and 

 quite fresh, and is found vigorous in all (and at all times of the year) at depths varying 

 from a few inches to 2 fathoms. 



Ripe embryos, which closely resemble those of L. lacustris (p. 49) in colour, 

 size and external form, were found in a sponge growing on a leaf of Halophila at 

 Barkuda Id. in July. Gemmules were seen only in specimens taken in fresh water 



1 In Herdman's Ceylon Pearl Fisheries, III, p. 131 (1905) 



