6. THE PHYLA PORIFERA, CNIDARIA AND PLATYHELMINTHES
247
anterior to and on each side of pharynx; large penetration glands
(Lebour depicts four on each side) on each side of ventral sucker and
which empty to the exterior near anterior sucker via four long ducts ;
FIGS. 151-158. Larval allocreads. (151) Older redia of Neophasis ptailla enclosing
developing cercariae; (152) young redia of N. pusilla; (153) young N . pusiEla
oercaria with tail; (154) fully developed tailless N. pusilla cercaria (redrawn after
Lebour, 191 1) ; (155) sporocyst of Cercaria neptuneae enclosing developing cercariae ;
(166) fully developed C. neptuneae (redrawn after Lebour, 1911) ; (167) sporocyst of
Cercariu ophicerca ; (1 68) fully developed C . opkicerca (redrawn after Palombi, 1934s).
DO, Developing ovary ; DT, developing testis ; ES, eye-spot ; E V , excretory
vesicle ; I N T , intestinal caecum ; PB, penetration gland; PH, pharynx.