A population of Trigoniulus corallinus (Gervis) in an open land rich in organic matter is studied for a year. Population density and biomass ranged from 2.13 to 56.31per m2 and 1026.38 to 8494.38 per m2 respectively. Various indices showed that population of T. corallinus is aggregated in distribution in the peak period of their abundance and this is due to patchy distribution of food, soil moisture and sexual attraction. Monthly age structure showed adult and late stadia are abundant in June, October and November while August population covered all the stadia.
In the developmental stages, length and width progression factor of T. corallinus ranged from 1.11 to 1.98 (mean 1.43) and 1.10 to 1.56 (mean 1.31) respectively. Weight progression factor in female is higher compared to that of male and this may due to more accumulation of egg forming tissue in female. Population density and biomass is significantly correlated with minimum temperature and rainfall.