1915-] Fauna of the Chilka Lake : Sponges. 35 



but this is not the case in Indian waters. I figure on plate iv a fragment of an 

 oyster-shell from Manikpatna destroyed by it. 



In the Chilka L,ake C. vastifica is abundant in the oyster-beds of the outer 

 channel. We found it in a flourishing condition both in September, 1913, when 

 the water was fresh or practically so, and in March, 1914, when it was as salt as 

 that of the Bay of Bengal (sp. gr. 10265). In the main area, towards the south 

 end of the lake, we took a few shells in which it occurred in February, March, and 

 November in water of a sp. gr. of from roo6 to i-oio. In the outer channel it was 

 always obtained in the shells of Ostrea, in which it was also found in the Ennur back- 

 water and the Adyar river near Madras in October, 1913; whereas in the main area 

 of the Chilka Lake it was only seen alive in shells of Purpura (Thais) carinifera. 

 In the latter region, however t burrows that agree with those made by it in oyster- 

 shells elsewhere were noticed in dead shells of Placuna and Ostrea. 



At both seasons of the year at which we took this species in the outer channel 

 its burrows contained many gemmules as well as living sponge-tissue, and were 

 numerous and of a relatively large size ; but examples found in shells of Purpura 

 in and in the neighbourhood of Rambha Bay contained few gemmules and were 

 otherwise feeble, though their spicules were well-developed and typical. Curiously 

 enough, C. vastifica shares with a deep-sea species of its genus (C. annulifera, 

 Annandale 1 ) the power of producing gemmules. Their utility is, I believe, in both 

 cases connected with the fact that the shells in which the sponge makes its excava- 

 tions are liable to be invaded by other boring sponges or covered over by species of 

 encrusting or parasitic habits. We found numerous examples of Laxosuberites aquae- 

 dulcioris on the outside of oyster-shells whose substance was permeated by the 

 galleries of C. vastifica. Where the Suberitid was very thin the excavator main- 

 tained itself alive and thrust its papillae right through the substance of the encrust- 

 ing form, but this became impossible as the latter grew thicker and the hidden 

 sponge was soon, overwhelmed. Encrusting sponges that coat small areas such as 

 the external surface of shells cannot be long-lived and it is not improbable that the 

 gemmules lie concealed in the interior of the shell when their parent-sponge is over- 

 whelmed, and sprout in situ if favourable conditions return. 



Family SUBERITIDAE. 

 Genus SUBERITES, Nardo. 



1900. Suberites, Topsent, Arch. Zool. exp'erim. (3) VIII, p. 224. 



The genus Suberites as now restricted consists of massive sponges with a con- 

 fused skeleton, without detachable ectosome, but with vertical bunches of spicules 

 on the surface. Although a considerable number of Indian species were assigned to 

 it in days when the name had a much wider significance, only three that have 

 hitherto been recorded from Indian seas can now be assigned to the genus : Suberites 



1 Rec. Ind. Mus. XI, p. 12, pi. i, fig. 2 (1915). 



