Cercaria myae sp. nov., a Fork-Tailed Larva from the Marine Bivalve, Mya arenaria

Cercaria myae has been found in three of 910 specimens of the soft clam, Mya arenaria, collected in the vicinity of Newburyport, Mass. Two infections were found upon dissection and examination of 143 preserved specimens which had been collected in July, 1949. The remainder of the material consisted of many smaller collections of living specimens. These, too, were examined by dissection since the material was being utilized for several independent studies. The third infection was found in a May, 1951 collection and the description to follow is based mainly upon that source.