A HISTOLOGICAL STUDY OF SYNDISYRINX FRANCISCANUS. GEN. ET SP. NOV., AN ENDOPARASITIC RHABDOCOEL OF THE SEA URCHIN, STRONGYLOCENTROTUS FRANCISCANUS

Abstract

SYNDISYRINX franciscanus*, a rhabdocoel intestinal parasite, family Umagillidae, is the first new genus and species of this family to be descr. from the Western Hemisphere. These worms were collected in Monterey Bay, California. Distinguishing characteristics are a single intestine, paired and lobed ovaries and testes, a single-walled cuticular penis, and the presence of a bursa seminalis connected to the seminal receptacle and bursal canal (vagina) by two cuticular tubules. General similarity of morphological structure indicates a close relationship to Syndesmis echinorum. A superficial similarity between the "mouth pieces" of acoels and the cuticular tubes in the bursal complex of Umagillidae is discussed; however, homologous origin of these structures is considered improbable. By special permission, the revised and hitherto unpublished terminology of L. H. Hyman relating to this group is introduced.