PLATE IV. 
Figs. 1-5. Polycyclus lamarchi, n. sp. 
Figs. 6-11. Polycyclus Jeffrey si, n. sp. 
Figs. 12-18. Sarcohotrylloides wyvillii, n. sp. 
a. Anus. 
at. Atrial aperture. 
h.c. Blood-corpuscle. 
br. Branciiial aperture. 
d.l. Dorsal lamina. 
d.t. Dorsal tubercle. 
en. Endostyle. 
gm, gm'. Buds in different stages of deve- 
lopment. 
i.l. Internal longitudinal bar of 
branchial sac. 
m. Mantle. 
n.g. Nerve ganglion. 
te. (Esophagus. 
pig. Mass of pigmented cells. 
p.p. Peripharyngeal band. 
r. Eectum. 
sg. Stigmata of branchial sac. 
Sphincter. 
■ st. Stomach. 
t. Test. 
t.k. Terminal bulb on vessel in test. 
tn. Tentacles. 
tr. Transverse vessel of branchial 
sac. 
V. Vessel in test. 
z. Prebranchial zone. 
Fig. 1. 
Fig. 2. 
Fig. 3. 
Fig. 4. 
Fig. 5. 
Fig. 6. 
Fig. 7. 
Fig. 8. 
Fig. 9. 
Fig. 10. 
Fig. 11. 
Fig. 12. 
Fig. 13. 
Fig. 14. 
Fig. 15. 
Fig. 16. 
Fig. 17. 
Fig. 18. 
Colony of Polycyclus lamarchi; natural size. 
Anterior part of Ascidiozooid of Polycyclus lamarchi, seen from the branchial 
sac; magnified (S., 1 inch). 
Part of the dorsal region of an Ascidiozooid of Polycyclus lamarchi; magnified 
(S., 1 inch). 
Surface view of the anus of Polycyclus lamarchi; highly magnified (S., ^ inch). 
Optical section of the anus of Polycyclus lamarchi; highly magnified (S., ^ inch). 
Colony of Polycyclus jeffreysi; natural size. 
An Ascidiozooid of Polycyclus jeffreysi, seen from the right hand side; 
magnified (S,, 1 inch). 
Diagram of the vessels in the test of Polycyclus jeffreysi; magnified (S., 1 inch). 
Part of the branchial sac oi Polycyclus jeffreysi, seen from the interior; magnified 
(S., 1 inch). 
Anterior part of an Ascidiozooid of Polycyclus jeffreysi, seen from the branchial 
sac; magnified (S., 1 inch). 
The atrial siphon of Polycyclus jeffreysi; highly magnified (S., ^ inch). 
Colony of Sarcohotrylloides wyvillii; natural size. 
Vessels from the test of Sarcohotrylloides wyvillii, showing the contained buds; 
magnified (S., 1 inch). 
Part of the branchial sac of Sarcohotrylloides wyvillii, seen from the exterior ; 
magnified (S., 1 inch). 
Diagram showing the arrangement of the Ascidiozooids in the test of Sarco- 
hotrylloides ivyvillii; magnified (S., 1 inch). 
Tailed larva of Sarcohotrylloides wyvillii, seen from the dorsal surface; magnified 
(S.j 1 inch). 
Tailed larva of Sarcohotrylloides wyvillii, seen from the side; magnified 
(S,, 1 inch). 
Portion of the tail of the larva of Sarcohotrylloides wyvillii, showing the large 
cells forming the urochord; highly magnified (S., ^ inch). 
