PLATE VI. 
Colella pedunculata, Quoy and Gaimard. 
br. Braucliial aperture. 
m. Endostyle 
l. V. Fine longitudinal vessels of bran- 
chial sac. 
m. Mantle. 
m. b. Muscle band in mantle. 
n. g. Nerve ganglion. 
p.p. Peripharyngeal band. 
sg. Stigmata of branchial sac. 
sg. c. Ciliated cells bounding’stigmata of 
branchial sac. 
sph. Sphincter. 
Test. 
tr. Transverse vessel of branchial sac. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig- 
Fig. 
Fig. 
2 . 
3. 
4. 
6 . 
8 . 
Fiff. 9. 
P’ig. 10. 
Fig. 
Fig. 
Fig. 
Fig- 
Fig. 
Fig. 
Fig. 
Fig. 
1. Part of the surface layer of test of Colella pedunculata, showing the apertures; 
magnified (S., 1 inch). 
Part of the anterior end of an Ascidiozooid, showing the branchial siphon; 
highly magnified (S., i inch). 
Part of the anterior end of an Ascidiozooid, from the left side, showing the 
branchial siphon in a contracted condition ; highly magnified (S., ^ inch). 
Part of the thorax of an Ascidiozooid, seen from the right side and ventral edge; 
highly magnified (S., ^ inch). 
5. Part of the mantle of Colella pedunculata, showing the muscle bands, from a 
young Ascidiozooid ; highly magnified (S., inch). 
Part of the mantle of Colella pedunculata, from an adult Ascidiozooid ; highly 
magnified (S., ^ inch). 
Part of the mantle of the incubatory pouch, showing the ectoderm ; highly 
magnified (S., inch). 
One of the ectoderm cells, showing the long process which runs into the test ; 
more highly magnified (Z., xV)- 
Part of the squamous epithelium lining the mantle, seen in surface view ; highly 
magnified (S., inch). 
Part of the branchial sac ; magnified (S., 1 inch). 
11. A small part of the branchial sac ; highly magnified (S., ^ inch). 
12. A small part of one of the fine longitudinal vessels of the branchial sac, showing 
the ciliated cells bounding the stigmata ; more highly magnified (S., ^ inch). 
13. A small part of a fine longitudinal vessel from another branchial sac, showing a 
difierent shape of ciliated cell on the stigmata ; highly magnified (S., ^ inch). 
1 4. The side of one of the fine longitudinal vessels, seen from one of the stigmata ; 
highly magnified (S., ^ inch). 
1 5. A transverse section of two of the fine longitudinal vessels from the branchial 
sac; highly magnified (S., ^ inch). 
16. Part of a branchial sac of a young Ascidiozooid; highly magnified (S., inch). 
D.L. indicates the dorsal and En. the ventral edge. 
17. A small part of a young branchial sac ; more highly magnified (S., ^ inch). 
18. The dorsal part of the branchial sac of a young Ascidiozooid ; highly magnified 
(S., ^ inch). 
