the study of a speceis of bivalve molluscs from the qom formation

the species introduced in this report belongs to the family amusiidae,and was found among the e member of blue marls of the qom formation(dochah and dobaradar areas). this species has already been studied in the miocene sediments of syria, lebanon, vienna region, poland, portugal, morraco and malta, however, no report has yet been published abolk it in iran. the valves of the shell are rounded and equal in size, and the dimension of the shell does not show considerable change, e.g. the ratio betwen the length and the height(l/h) varies from 0.94 to 107 mm., the species was appeared in miocene period, well distributed in the pliocene, and disappeared by the end of this period. it is considered to be endemic of the mediteranean sea..