1 88 Papers from the Marine Biological Laboratory at Tortugas. 



Pcdibothrium brcvispine gen. et sp. nov., from Ginglimostoma cirratum. 



20, 21. Single hooks, different views; actual length 0.068 mm. 



22. Free, ripe segment, balsam; actual length 2.8 mm. 



PLATE 4. 

 Pedibothrium brevispine, continued, from Ginglimostoma cirratum. ' 



23. Pair of hooks; actual length 0.064 mm. 



24. Head, balsam; maximum diameter 0.21 mm. 



25. Free, ripe segment with cirrus exserted; actual length 2.8 mm. 



AcanthobotJirium brei'issime sp. nov., from Dasyatis say. 



26. Strobile, balsam; actual length 1.43 mm. The enlargement at the base of the 



neck is probably a contraction character. 



27. Head, balsam; length of head 0.25 mm. 



28. Single hook. 



29. Pair of hooks, prongs broken. 



Actual length in figs. 28 and 29, 0.05 mm. 



PLATE 5. 

 Rhynchobothrium simile sp. nov., from Ginglimostoma cirratum. 



30. Head, neck and anterior part of strobile ; lateral view of the head ; actual diameter 



of neck behind head 0.6 mm. 



31. Head, showing margins of bothria; diameter of neck behind head 0.65 mm. 



32. Proboscis, near base; diameter, exclusive of hooks, 0.19 mm. 



33. Proboscis, near base, showing side opposite to that shown in figure 32; diameter, 



exclusive of hooks, 0.17 mm. 



34. Proboscis 0.8 mm. from base; diameter, exclusive of hooks, 0.17 mm. 



35. 36. Two types of hooks shown in fig. 34, more enlarged; lengths 0.16 and 0.17 mm. 



37. Last segment, in glycerin ; length 2 mm. 



PLATE 6. 

 RJiynchobotJirium simile sp. nov., continued. 



38. Base of proboscis; diameter, exclusive of hooks, 0.17 mm. 



Rhynchobotlirium lincatum sp. nov., from Ginglimostoma cirratum. 



39. Head and neck, balsam; length of head and neck 3.5 mm. 



40. Proboscis at base; diameter, exclusive of hooks, 0.05 mm. Partly diagrammatic. 



41. Proboscis, middle; diameter, exclusive of hooks, 0.04 mm. 



42. Proboscis, near apex ; diameter, exclusive of hooks, 0.04 mm. 



43. Segment toward posterior end of strobile; length i mm. 



Rhynchobothrium curtnin sp. nov., from Galcoccrdo tigrinus. 



44. Head, neck, and anterior part of strobile, alcoholic, showing marginal view of 



bothrium ; length of head 0.20 mm. 



45. Lateral view of bothrium, and anterior end of strobile, alcoholic; length of both- 



rium 0.19 mm. 



46. Same view of another specimen mounted in balsam; length of bothrium 0.19 mm. 



47. Last segments of strobile mounted in balsam; breadth of last segment 0.33 mm. 



PLATE 7. 



Rhynchobotlirium c.rilc sp. nov., from Galeocerdo tigrinus. 



Head and neck sketched from alcoholic specimens; diameter of neck, anterior, 

 0.28 mm. 



