35. Bivalve Molluscs injuring Brickwork in the 
Calcutta Docks, 
By N. Annanpatr, D.Sc., F.A.S.B., CIE. (Zoological 
Survey of India). 
of the dock. The damage was not very serious and it was 
evident that the mollusc had been able to attack only those 
parts of the wall at which the blue glaze on the bricks had 
been worn away or abraded. Moreover, all the individuals 
discovered had died after penetrating to a depth of about half 
a brick, killed possibly either by some change in the salinity 
of the water, or more probably by the flowing into the docks 
of some chemical waste product. Conditions may, however, 
have been unfavourable for reproduction. Had the activities 
of the mollusc continued uninterrupted for a long perio 
outer wall of the entrance had also been attacked, always 
below the habitual water-level. The brickwork is about thirty 
years old and showed no sign of more than one attack, which 
was probably carried out by a single generation of molluscs, 
or at most by one flourishing and a second more feeble 
generation. 
of these were still alive. One of the species (M odiola striatula) 
has already been reported as doing injury to brickwork in the 
Calcutta docks by insinuating itself into cracks and joints and 
there increasing in numbers and bulk. Were large masses 0 
this mussel or any other living organism to establish themselves 
in the Pholad’s holes they would undoubtedly aid in the further 
disintegration of the bricks by breaking down the thin parti- 
tions left between the different burrows. 
Young of the Martesia had evidently been assisted in 
