VI. SOME SPONGES ASSOCIATED WITH 



GREGARIOUS MOLLUSCS OF THE 



FAMILY VERMETIDAE. 



By N. Annandale, D.Sc, F.A.S.B., Superintendent of the 

 Indian Museum . 



Among the most interesting of the specimens received at the 

 Indian Museum as a resalt of the work of the trawler " Golden 

 Crown " in the Bay of Bengal are a number of rocky masses con- 

 sisting of the contorted and worm-like shells of molluscs of the 

 family Vermetidae embedded in sponges. Unfortunately they did 

 not reach us until they had been exposed to the air for some days 

 and were m a dry or putrid condition, and only a few broken 

 fragments were preserved in spirit ; but as the^^ offer material for 

 certain observations and speculations of a general as well as a tax- 

 onomic nature I have prepared the following notes regarding them. 



I.— GENERAL. 



The masses received at the Museum can be readily separated 

 into two series, one consisting of shells with strongly serrated 

 external ridges and of sponges of an intense black colour and only 

 of moderate hardness, the other of much smoother shells embedded 

 in sponges that are of stony hardness and either of variegated 

 grey and purple or of some shade of red, orange or yellow. 



The masses of the first kind were apparently taken only off 

 Gopalpur in the Ganjam district of Madras at depths between 30 

 and 38 fathoms. Only three specimens were sent us, but probably 

 more were brought up in the trawl and thrown awa}'. A descrip- 

 tion of the largest and most perfect specimen preserved (pi. viii, 

 fig. i) will appl}^ equally well, so far as general characters are con- 

 cerned, to the others also. 



The mass is roughly heart-shaped, measuring 40"8 cm. in 

 length, 40'8 cm, in greatest breadth and i6'6 cm. in depth, and 

 weighing 9 lb. 15 oz. dry. It is possible to distinguish the upper 

 from the basal surface by the fact that the shells open, in a more or 

 less horizontal direction, on the former ; the latter is irregular but 

 nearly flat as a whole, there is no sign of it having been attached 

 to an3' foreign object and .the mass appears to be complete in itself, 

 not merely a part of a larger mass. The shells, of which several 

 hundreds are present, appear to radiate outwards from a number of 

 different centres, but each is twisted and contorted in a manner 

 different from its neighbour, although the main course of all is 



