88 Papers from the Marine Biological Laboratory at Tortugas. 



Cymatocarpus undulatus Looss. 



Fig. 15. Dorsal view of flattened specimen, life; length 3.57 mm. Ova in 

 folds of uterus on right side and in posterior folds of left side dark 

 brown, those in other folds of left side yellow. Metraterm sur- 

 rounded by gland-cells resembling prostate gland. 



Fig. 16. Ventral view, life, showing details of the genitalia. 



Fig. 17. Transverse section of cirrus-bulb, showing prostate cells, part of 

 seminal vesicle, and secretion in wall of prostatic duct; diameter 

 0.30 mm. 



Fig. 18. Transverse section of neck showing esophagus and excretory vessel; 

 diameter 0.86 mm. 



Fig. 19. Transverse section just behind the bifurcation of the intestine; 

 diameter 0.87 mm. 



Plate 3. 



Cymatocarpus undulatus, continued. 



Fig. 20. Ova; length 0.024 mm. 



Fig. 21. Excretory pore and surrounding glandular cells; diameter of pore 

 0.04 mm. 



Fig. 22. Portion of transverse section of neck, showing yolk-forming cells 

 and accumulating yolk in central parenchyma. Thickness of 

 worm at this point 0.15 mm. y, accumulating yolk. 



Orchidasma amphiorchis (Braun) Looss. 



Fig. 23. Ventral view of specimen mounted in balsam; length 2.3 mm. 



Fig. 24. Details of genitalia, dorsal view; breadth of body at level of antenor 



testis 0.63 mm. 

 Fig. 25. Ova; diameter 0.039 mm. 

 Fig. 26. Spines from cirrus; length 0.05 mm. 

 Fig. 27. Spines from metraterm; length 0.040 mm. 

 Fig. 28. Spines from distal end of metraterm; length 0.05 mm. 



Trematodes from Fish. 

 Helicometra torta sp. nov., from Epinephelus striatus. 



Fig. 29. Ventral view, life, flattened; length 4 mm. 



Plate 4. 

 Helicometra torta, continued. 



Fig 30. Dorsal view of another specimen, not much flattened; length t. 5 7 mm. 

 Fig. 31. Surface view, life, ventral; length 2 mm. 



Fig. 32. Details of ovary etc., of another specimen, life, ventral view, diam- 

 eter of posterior testis 0.27 mm. k, ootype. 

 Fig. 33. Portions of ovary, shell-gland and yolk-reservoir, with ootype, from 

 section; diameter of ootype 0.03 mm. e', germ cell entering ootype. 



Helicometra execta sp. nov. 



Fig. 34. Dorsal view, life, details added from mounted specimen; length 

 1.90 mm. 

 This and the following figures, with the exception of 38 J, 

 from Hamulon plumieri. 



Fig. 35. Ventral view of another specimen; length 1.50 mm. 

 Fig. 36. Cirrus-pouch and metraterm from longitudinal section, n, cells 

 surrounding genital aperture. 



Plate 5. 

 Helicometra execta, continued. 



Fig. 37. Transverse section of cirrus-pouch and metraterm at anterior border 



of ventral sucker. 

 Fig. 38. Ovary and testes from different specimens. 

 Fig. 38a. Ovary in contact with single testis, latter not lobed. 



