Virgulate Xiphidiocercariae from Nitocris dilatatus Conrad

Nine species of virgulate xiphidiocercariae are reported from the river snail Nitocris dilatatus in West Virginia. These include Cercaria adoxovirgula Hall, C. tremaglandis Hall, C. stenodorya sp. n., C. blennifera sp. n., C. dolomeda sp. n., C. dracodysiana sp. n., C. apatema sp. n., C. polypyreta sp. n., and C. astraeadena sp. n. Seven of the nine species entered arthropods. Evidence of attachment and entry was observed in thionin and toluidine-blue-stained serial sections of insects recently exposed to Cercaria stenodorya, C. polypyreta, C. adoxovirgula, and C. tremaglandis. A mucoid substance from the virgula organ aided in attaching the cercariae to insect naiads and in lubricating the cercariae during entry.