PLATE XIII. 
In all tlie 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. 
S 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 IT., which magnifies 220 diameters, if the contrary be not expressly stated. 
Figs. 1-5. Myzostoma cysticolum, n. sp. 
-3. Three cysts from Actinometra meridionalis, var. carinata, P. H. C. ; magnified 
5 diameters (figs. 1 and 3 drawn from both sides). 
4. Cross section through such a cyst, containing a dwarf male ($ ) and the large 
female ( ? )• This latter is folded together, so that the lateral parts, lying 
quite close together, enclose a canal which serves as a “brood pouch” for the 
eggs. 
5. The dwarf male, seen from the ventral side; magnified about 75 diameters. 
Figs. 6-16. Myzostoma tenuispinum, n. sp. 
6. A cyst from Antedon incequalis. P. H. C. ; magnified 7 diameters. From both 
sides (A, B ), and broken open (C), to show the male and the female within. 
7. The dwarf male, from the ventral side ; magnified about 75 diameters, r., the 
rectum. 
8. The female, from the ventral side ; magnified about 12 diameters. 
9. Diagrammatic cross section of the same. 
10. Diagrammatic longitudinal section of the same ; the upper is the dorsal surface. 
Figs. 11-14. Four other cysts from Antedon incequalis, P. H. C. ; magnified diameters 
(14, A, from the side and B, from the dorsal side). 
Fig. 15. A large cyst upon the base of an arm of Antedon angusticalyx, P. H. C., in 
three different views, magnified 7 diameters, having a main aperture (x) 
and two secondary apertures (y, z). 
Fig. 16. An arm cyst of Antedon incisa, P. H. C., twice enlarged (copy of a figure made 
by Dr. P. H. Carpenter, and published here with his permission). 
Figs. 1 
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