256 MR. F. D. DYSTER ON PHORONIS HIPPOCREPIA. 
EXPLANATION OF THE PLATE. 
Tas. XLIV. 
n Figs. 1,2, 3. Side, vertical, and front views of Phoronis hippocrepia. 
». Fig.4. a. Lophophore. 
b. Œsophagus. 
c. Hæmal vessel overlying æsophagus. 
d, d, d. Ova overlying hæmal vessel. 
6,6. Branches of hæmal vessel opening into sinus of lophophore. 
Af. Venous branches uniting beneath the cesophagus, and forming neural vessel. 
9,9. Ridges forming terminations of oviduct. 
À, À. Uncertain organs. 
Fig. 5. View of vascular system. 
a. Lophophore. 
b. Venous branches. 
c. Neural vessel. 
d. Hæmal vessel. 
e; €. Capillary loops connecting neural and hæmal vessels. 
J. Œsophagus. 
g. Mouth with crescentic lip. 
h. Tentacula with twigs opening into sinus of lophophore. 
Fig. 6. Diagram of lophophore seen from above. 
a. Lophophore. 
b. Bases of tentacula. 
c. Mouth covered with crescentic lip. 
d. Anus. 
e. Terminations of oviduct. 
Fig. 7. Blood-corpuscles, magnified 460 diameters. 
Fig. 8. Ovary. 
Fig. 9. Spermatozoa, magnified 460 diameters. 
Fig. 10. Ovum just separated. í 
Figs. 11, 12, 13. The same in more advanced stages of development, the last about 48 hours old. 
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