EXPLANATION OF PLATES. 



The following reference letters have the same significance in the different 

 figures unless otherwise indicated. 



a. oral sucker. o. ovary. 



b. ventral sucker. oe. esophagus. 



c. cirrus, or ductus ejaculatorius. p. prepharynx. 

 on. circular muscle. ph. pharynx. 

 cp. cirrus-pouch. pr, prostate. 



d. subcuticular gland-cells; in many pr'. duct of prostate. 



cases these are interpreted to be sg. shell-gland, 



yolk-forming cells. sr. seminal receptacle. 



dm. diagonal muscles. sv. seminal vesicle. 



e. ova. t. testes. 



exp. excretory pore. tin. transverse muscle. 



exv. excretory vessel. u. uterus. 



g. genital aperture. vd. vas deferens. 



i. intestine. vg. vitelline gland. 



Int. longitudinal muscle. yd. yolk-duct. 



m. metraterm, i.e., the ejaculatory por- yr. yolk-reservoir, 

 tion of the uterus. 



Figures i to 28 inclusive are from material collected from the loggerhead 

 turtle; the remaining figures illustrate trematodes from various Tortugas fishes. 



Plate i. 

 Cricocephalus delitescens Looss. 



Fig. 1. Ventral view, life; some details added from stained and mounted 



specimen; intestine somewhat diagrammatic; length 4.6 mm. 



/, postero-lateral pit ; k, muscular ridge. 

 Fig. 2. Enlarged view of one of the characteristic pits situated at lateral 



angles of trtmcated posterior end; actual diameter of pit 0.010 



mm. From specimen mounted in balsam. 

 Fig. 3. Ovum; length of egg 0.029 mm., length of filament 0.12 mm. 



Immature dislomum. Related to Caly codes Looss. 



Fig. 4. Ventral view, life; a few details added from mounted specimen; 



length 1.5 mm. 

 Fig. 5. Ventral view of anterior end of same; diameter of head 0.34 mm. 

 Fig. 6. Dorsal view of same. 



Pachypsolus ovalis sp. now 



Fig. 7. Ventral view. The specimen was flattened and the positions of some 



of the organs are somewhat changed from the normal; length 3.36 



mm. 

 Fig. 8. Dorsal view of specimen reconstructed from sections. 

 Fig. 9. Transverse section of body at posterior edge of ventral sucker; 



diameter 0.84 mm. 

 Fig. 10. Transverse section at level of testes. Excretory vessels unite in next 



section posterior to this; diameter 0.88 mm. 



Plate 2. 

 Pachypsolus ovalis, continued. 



Fig. 11. Nearly transverse section of the pharynx; diameter 0.14 mm. 

 Fig. 12. Sagittal section, diagrammatic, of cirrus-pouch, etc. 

 Fig. 13. Ova; maximum length 0.048 mm. 



Fig. 14. Dorsal view, life, showing branching and anastomosing excretory 

 vessels; length 4.4 mm. 



87 



