FISH ENTOZOA FROM YELLOWSTONE PARK. 563 



Plate 65. 

 Monohotlirium terebrans sp. nov^. 



Fig. 20. Longitudiiial section of body wall near posterior end; e, epidermis; c, 

 cuticle; I, longitudinal subcuticular fibers; sc, subcuticular fibro- 

 granular layers ; n, nucleated cell ; Im, longitudinal nuiscle layer ; (/, 

 nucleated cells of germ gland, X 300. 



Fig. 21. Longitudinal section through vas deferens; vd, vas deferens; a, masses of 

 spermatozoa, X 37.5. 



Encysted disfom inn from Lei^ciscns atrarius. 



Fig. 22. Young distomum in cyst, from body cavity of Lenciscns atrarius, X 60. 

 Fig. 23. Same liberated from cyst, X 60; w, terminal pore of water vascular system. 

 Fig. 24. Cyst with three distoma, from same host. 

 Fig. 25. Cyst with two distoma, from same host. 



Distomum lanreatnm Zeder. 



Fig. 26. Ventral view of specimen in carbolic acid and turpentine; X 24, a, mouth 

 and anterior sucker; j>/(, pharynx; c, cirrus; b, ventral sucker; o, eggs 

 in uterus, walls of latter organ not clearly defined in specimen; ov, 

 ovary; vd, vitelline duct; t, testes; vg, vitelline glands. 



Fig. 27. Marginal view of another specimen, X 22. 



Fig. 28. Ventral view of anterior end. 



^''ig. 29. Dorsal view of same specimen figured in No. 28. 



Fig. 30. Ventral view of anterior end of specimen 4.5 mm. in length, x 45. 



Echinorhynclin.s (jlobiilosus f Rud. 



Fig. 31. Sketch of a fragment, the anterior end of an echinorhynchus from Salmo 

 mi/kiss; length of fragment, 3 mm. .Specimen in glycerin when 

 sketched; anterior end of proboscis apparently collapsed. 



Fig. .32. Hooks of same near base of proboscis. 



Plate 66. 

 Echinorhynclius tuherosus Zeder. 



Fig. .33. rt. Anterior end of 9 X 12; a, posterior end of same, X 12; b, hooks of 

 proboscis; c, same, specimen in caustic potash, showing basal sup- 

 ports, highly magnified. 



Fig. .34. Portion of proboscis of 9 in glycerin. 



Fig. .35. Anterior end of 9» optical section, 1, lemnisci; s, sheath of proboscis; n, 

 cuticular pore; o, eggs; 6, ovarian masses, x 14; ova X about 30. 



Fig. 36. Transverse section through anterior end, c, cuticle; /, longitudinal sub- 

 cuticular fibers; s c, subcuticular grannlo-fibrous Liyer; rm, circular 

 muscles; /m, longitudinal iiuiscles forming a sheath for the lemnisci ; 

 U, lemnisci; r, longitudinal vessel of same; s, wall of proboscis sheath; 

 ng, nerve ganglion; r, retractor muscle of proboscis. 



Fig. 37. Transverse section through nerve ganglion, more highly magnified than 

 Fig. 36; n g, nerve ganglion. 



Fig. 38. Optical section of $ in glyc(;rin ; a, b, c, hooks of proboscis. Other 

 specimens were observed in which the lemnisci were relatively con- 

 siderably longer than shown in this sketch. X 0. 

 Figs. 33 to 38 sketched from specimens from Catostomus ardens. 



Fig. 39. Head of ^ from Leuciscus atrarius. 



