The biology of two species of Donax, D. incarnatu~ Gme|in
and D. spiculum R, eeve on two beaches in south west India is
described. Two year groups of D. incarnatus were present on
both beaches, from settlements during the monsoon period in
1967 and t968. At Shertallai, both groups were studied through
the year, and data on growth, mortality and production are
presented. At Cochin, the rate of growth was slower and the
maximum size attained smaller, but mortMity during the early
monsoon precluded study of D. incarnatus through a futl year.
D. spiculum occurred ar Cochin mainly during the pro-monsoon
period, and at ShertaIlai during the post-monsoon. The
species has a shorter life-span than D. incarnatus, but its
irregular occurrence did not allow detailed production estimates.