PLATE XI. 
Colella thomsoni, n. sp. 
enib. A bud. 
en. Endostyle. 
h. m. Horizontal membrane of branchial 
sac. 
1. Dorsal languet. 
l. v. Fine longitudinal vessels of bran- 
chial sac. 
m. Mantle. 
m.h. Muscle band in mantle. 
p.p. Peripharyngeal band. 
r. Eectum. 
sg. Stigmata of branchial sac. 
t.c. Test cells. 
t.m. Test matrix. 
tr. Transverse vessel of branchial sac. 
Fig. 1. Section through the test of Colella thomsoni; highly magnified (S., i inch). 
Fig. 2. Part of the body of the Ascidiozooid, seen from the right hand side ; magnified 
(S., 1 inch). 
Fig. 3. Part of the mantle and endostyle, showing the arrangement of the muscle 
bands ; highly magnified (S., inch). 
Fig. 4. Surface view of the ectoderm of Colella thomsoni; highly magnified (S., ^ inch). 
Fig. 5. Part of the branchial sac ; highly magnified (S., ^ inch). 
Fig. 6. A small portion of the branchial sac ; more highly magnified (S., ^ inch). 
Fig. 7. Another small portion of the branchial sac; still more highly magnified 
(S., ^ inch, enlarged). 
Fig. 8. The anterior part of the endostyle ; magnified (S., 1 inch). 
Fig. 9. Part of the dorsal region of the branchial sac, showing two of the languets ; 
highly magnified (S., inch). 
Fig. 10. The same region in another specimen, showing the languets ; highly magnified 
(S., ^ inch). 
