PLATE I. 
In all the Plates the following letters have the same signification. 
c. Marginal cirrus. • 
cl. Cloacal papilla or opening. 
i. Intestine, 
m. Mouth. 
ma. Manubrium of the supporting stalk of the hook-apparatus. 
ov. Ovarium. 
p. Parapodium. 
ph. Pharynx. 
s. Sucker. 
t. Testicle. 
u. Hook of the hook-apparatus. 
$ Male genital papilla or opening. 
Note . — The coloured drawings show the object seven times magnified ; the uncoloured drawings are drawn with the 
Oberhauser camera and objective 0 (Seibert and Krafft), which magnifies 40 diameters, the hook-apparatus with camera and 
objective IV., which magnifies 220 diameters, if the contrary be not expressly stated. 
Figs. 1-17. Myzostoma horologium, n. sp. 
Figs. 1,2. The animal from the ventral side. 
Fig. 3. Piece from a transverse section of the sucker, cu., cntis ; dom., dorso- ventral 
muscles ; e., epithelium of the surface of the body; s^, epithelium of the 
sheath of the sucker ; se., epithelium of the retracted sucker. 
Figs. 4-14. Several variations in the pigmentation of the back. 
Fig. 15. A hook from the parapodium. 
Fig. 16. The supporting stalk, with its manubrium (ma.), the hook (u.) partly drawn. 
Fig. 1 7. The supporting stalk after having been treated with alkali. The manubrium 
(ma.) and the outer layer of the stalk (b.) dissolved into a finely granular 
substance. The more resistent central part (a.) of the latter still pre- 
served. 
Figs. 18-24. Myzostoma testudo, n. sp. 
Figs. 18, 19. Seen from the dorsal side, with the tubercles always in pairs, and the 
divided longitudinal elevation. 
Figs. 20, 21. Seen from the ventral side. 
Fig. 22. Diagrammatic cross section through fig. 19. 
Fig. 23. A small individual with a somewhat different sculpturing of the back. 
Fig. 24. Point of a hook-apparatus, ma., manubrium of the supporting stalk ; u., 
the hook. 
Figs. 25-29. Myzostoma alatum, Graff. 
25. The animal from the dorsal side. 
26, 27. The same from the ventral side. 
28. Diagrammatic cross section through fig. 27. 
29. Point of a hook-apparatus, ma., manubrium of the supporting stalk ; u., 
the hook. 
Fig. 
Figs. 
Fig. 
Fig. 
