Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 2 
Fig. 2 
Fig. 
Fig 
Foi 
Fig. 
bo 
bo 
bh bo bo 
te ge 
31. 
32. 
. 33. 
FISH ENTOZOA FROM YELLOWSTONE PARK. 563 
PLATE 65. 
Monobothrium terebrans sp. nov. 
Longitudinal section of body wall near posterior end; e, epidermis; ¢, 
cuticle; J, longitudinal subcuticular fibers; sc, subcuticular fibro- 
granular layers; », nucleated cell; Im, longitudinal muscle layer; g, 
nucleated cells of germ gland, x 300. 
Longitudinal section through vas deferens; vd, vas deferens; s, masses of 
spermatozoa, x 375. 
Encysted distomum from Leuciscus atrarius. r 
Young distomum in cyst, from body cavity of Leuciscus atrarius, X 60. 
Same liberated from cyst, x 60; w, terminal pore of water vascular system. 
Cyst with three distoma, from same host. 
Cyst with two distoma, from same host. 
Distomum laureatwm Zeder. 
Ventral view of specimen in carbolic acid and turpentine; Xx 24, a, mouth 
and anterior sucker; ph, pharynx; c, cirrus; b, ventral sucker; 0, eggs 
in uterus, walls of latter organ not clearly defined in specimen; ov, 
ovary; vd, vitelline duct; ¢, testes; vg, vitelline glands. 
Marginal view of another specimen, xX 22. 
. Ventral view of anterior end. 
. Dorsal view of same specimen figured in No. 28. 
Ventral view of anterior end of specimen 4.5 mm. in length, x 45. 
Echinorhynchus globulosus ? Rud. 
Sketch of a fragment, the anterior end of an echinorhynchus from Salmo 
mykiss; length of fragment, 3 mm. Specimen in glycerin when 
sketched; anterior end of proboscis apparently collapsed. 
Hooks of same near base of proboscis. 
PLATE 66. 
Echinorhynchus tuberosus Zeder. 
a, Anterior end of 9 x 12; d, posterior end of same, X 12; b, hooks of 
proboscis; ¢, same, specimen in caustic potash, showing basal sup- 
_ ports, highly magnified. 
Portion of proboscis of 2 in glycerin. 
Anterior end of 9, optical section, 1, lemnisci; 8s, sheath of proboscis; a, 
cuticular pore; 0, eggs; 6, ovarian masses, X 14; ova X about 30. 
Transverse section through eae end, ¢, caer 1, Jongitudinal sub- 
cuticular fibers; sc, subeuticular granulo-fibrous layer; cm, circular 
muscles; /m, longitudinal muscles forming a sheath for the lemnisci; 
U, lemnisci; v, longitudinal vessel of same; s, wall of proboscis sheath ; 
ng, nerve ganglion; r, retractor muscle of proboscis. 
. Transverse section through nerve ganglion, more highly magnified than 
Fig. 36; n g, nerve ganglion. 
. Optical section of g in glycerin; a, 6, c, hooks of proboscis. Other 
specimens were observed in which the lemnisci were relatively con- 
siderably longer than shown in this sketch. x 9. 
Figs. 33 to 38 sketched from specimens from Catostomus ardens. 
. Head of & from Leuciscus atrarius. 
