Wardle, W.J.Contributions in Marine Science2010-02-152010-02-151983http://hdl.handle.net/1969.3/19133pages 15-22.The sporocysts and non-ocellate trichocercous cercarial stages of two species of digenetic trematodes of the family Fellodistomidae are described from the gonad and digestive gland of estuarine bivalved molluscs in the Galveston Bay System, Texas. Cercaria tageli n.sp. develops in the stout razor clam Tagelus plebeius (Solander) and most nearly resemble Cercaria laevicardium (Martin, 1945). Cercaria rangiae n.sp. develops in the common rangia clam Rangia cuneata Gray and most nearly resembles Cercaria chiltoni Dollfus, 1925. The sporocysts of both species cause castration of their respective host.parasites; parasitism; hosts; Tangelus plebius; clams; Trematoda; TrematodaArticle