Plate 8. 



Sylon, Clistosaccus, Duplorbis and Scalpellum. 



ch chitin. Cls mantle openings, coll colleteric gland, ect ectoderm. Em embryos, gn ganglion. 

 lac lacunar tissue, mes mesentery, mes.can mesenteric canal, m mantle, m.c mantle cavity, ov ovary. 

 Ring ring of attachment, spl primary spermatocytes, sp'2 secondary spermatocytes. sp.3 spermatids and 

 spermatozoa, spd spermatids, spm spermatozoa, spg spermatogonia, st stalk, t testis, vise visceral mass. 

 visc.ect external epithelium of visceral mass, (f supposed complemental male. 



Fig. 1. Hippolyte fabricii with Sylon. Nat. size. 



Fig. 2. Sylon, viewed from dorsal or mesenterial surface. X 4. 



Fig. 3. Sylon, transverse section through anterior region of body. X 25. 



Fig. 4. Sylon, transverse section through body, in region of mantle openings (cl) and nervous ganglion (gn). 



X 40. 

 Fig. 5. Clistosaccus, ideal longitudinal section. 

 Fig. 6. Clistosaccus, transverse section through extreme anterior region of body to show colleteric gland 



{coll). X 12. 

 Fig. 7. Clistosaccus, transverse section through middle of body. X 12. 

 Fig. 8. Clistosaccus, section through testis showing stages in spermatogenesis. X 700. 



Fig. 9. Calat/tura brachiata in ventral view, with three specimens of Duplorbis calathurae in marsupium. X 4. 

 Fig. 10. Duplorbis, whole specimen viewed from mesenterial surface. 

 Fig. 11. Duplorbis, whole specimen viewed from ventral or antimesenterial surface. 

 Fig. 12. Duplorbis, section taken longitudinally to morphological long axis, transversely to actual long 



axis of body, in the mesenterial middle line, showing mesenterial canal (mes.can), stalk (st) of attach- 

 ment, visceral mass (rise) and mantle cavity (me) etc. X 40. 

 Fig. 13. Duplorbis, section longitudinal to morphological long axis, showing colleteric gland (coll) of one 



side, visceral mass and ovary. X 175. 

 Fig. 14. Duplorbis, section similar to foregoing, but at an extremity of body, to show mantle cavity full of 



embryos and the supposed complemental male (q 1 ). X 40. 

 Fig. 15. Duplorbis, longitudinal section through mesenteric canal, showing histology. X 650. 

 Fig. 16. Duplorbis, transverse section through stalk and mesentery, showing mesenteric canal. X 80. 

 Fig. 17. Duplorbis, transverse section through stalk, where the latter enters body of host, showing opening 



of mesenteric canal into host. X 80. 

 Fig. 18. Duplorbis, transverse section through supposed complemental male in mantle cavity. X 650. 

 Fig. 19. Duplorbis, stages in spermatogenesis taken from supposed complemental male. X 1300. 

 Fig. 20. Scalpellum rulyare, transverse section through the body of a complemental male, showing mantle (m), 



testis etc., for comparison with Fig. 18. X 160. 

 Fig. 21. Scalpellum vulgare, stages in spermatogenesis taken from complemental male. X 1300. 



