108 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.64. 



Orygmatobothrium paulitni Linton, from Oaleocerdo arcticus. 



Fig. 11. Front view of bothrium, contracted, tlie suckers seen in optical sec- 

 tion ; balsam ; length 0.35. 



12. Four proglottides, showing tendency of genital apertures to lie many 



in succession on the same margin ; balsam ; breadth 0.5. 



13. Adult proglottis ; balsam ; length 1.68. 



Trilocularia gracilis Ollson, from Squalus acantliias. 



Fig. 14. Scolex ; balsam ; breadth 0.5. 



15. Front view of bothrium ; glycerine ; breadth 0.25. 



16. Portion of strobile, posterior end to right ; balsam ; breadth 0.17. 



17. Posterior end of same ; balsam ; breadth 0.14. 



Monorygma perfectum (van Beneden), from Somniosus brevipinna. 



Fig. 18. Transverse section of proglottis ; two sections of the series used ; 

 longer diameter of section 4. 



Platk 3. 

 Monorygma perfectum (continued). 



Fig. 19. Scolex and strobile ; balsam ; length 85. 



20. Scolex of same ; balsam ; diameter 3.5. 



21. Transverse section near anterior end of scolex (fifth section of series), 



showing rudiment of myzorhynchus, mz; maximum diameter 0.88. 



22. Tenth section of same series of sections of scolex ; longer diameter 1.57. 



23. Thirtieth section of series ((>5 sections in series) ; longer diameter 2.29. 



24. Vagina and cirrus pouch in fourth section from margin, in series of 



sagittal sections; greater diameter of cirrus pouch 0.17. 



25. Same, as seen in tenth section. 



26. Same, as seen in twentieth section. 



27. Vagina and cirrus pouch, the latter with three sections of the cirrus, 



as seen in the fortieth sections. 



28. Same in fiftieth section. 



29. Vagina and vas deferens, sixty-third section. Figures 24-29 drawn 



to same scale. 



30. Diagram of female genitalia reconstructed from sagittal sections. 



31. Egg, 0.09 by 0.03 in the two principal diameters. 



Plate 4. 



Acanthohothrium paulum Linton, from Raja eglanteria. 



Fig. 32. Pair of hooks; length 0.14. 



Acanthobothrium coronatum Rudolphi, from Raja stabuUforis. 



Fig. 33. Pair of hooks; length 0.11. 

 84. Bothrium; length 1. 

 35. Pair of hooks ; length 0.15. 



Phoreiohothrium labium Linton, from Carcharhinus obscurus. 



Fig. 36. Bothrium; balsam; length 0.30. 



37. Front view of scolex; balsam; maximum length of hooks 0.10. 



38. Marginal view of bothrium ; balsam ; length of bothrium 0.35 ; from 



C. Hmbatus. 



39. Pair of hooks; length 0.10. 



40. Spines from neck; maximum length 0.015. 



