Cerithidea hegewischi californica, a brackish-water snail, serves as first and second intermediate host. The complete excretory system of the cercaria was traced. Thirty-two flame cells in pairs were found on each side of the body. Metacercariae were found only in or adjacent to the radular mass. Adults were recovered from the small intestine of hatchery-raised chicks. Natural hosts in southern California are the avocet, Recurvirostra americana, and the black-bellied plover, Squatarola squatarola. Egg production begins when the adult worms are about 12 days old. Mlracidia hatch when 16 to 27 days old. Eight epidermal plate cells, instead of the previously reported 6, comprise the second tier in the miracidium.