PLATE XXII. 
Tylohranchion speciosum, n. sp. 
h.s. Blood sinus. 
d.t. Dorsal tubercle. 
d. 1. Dorsal lamina. 
ec. Ectoderm. 
g.t. Germinal tubule. 
h.m. Horizontal membrane of 
chial sac. 
1. Languet. 
m. h. Muscle band in mantle. 
0 . Ovum. 
p. Papilla. 
p.p. Peripharyngeal band. . 
sg. Stigmata of branchial sac. 
sph. Sphincter. 
t. c. Test cells. 
t.m. Test matrix. 
tn. Tentacles. 
tr. Transverse vessel of branchial sac. 
t.v. Spermatic vesicles. 
v.d. Vas deferens. 
Fig. 1. Colony of Tylohranchion speciosum; natural size. 
Fig. 2. K&cidiiozooidi o^ Tylohranchion speciosum ; natural size. 
Fig. 3. Another Ascidiozooid with much larger post-abdomen ; natural size. 
Fig. 4. Ascidiozooid, seen from right hand side ; magnified (S., 1 inch). 
Fig. 5. Part of test of Tylohranchion speciosum; highly magnified (S., -g- inch). 
Fig. 6. Part of endostyle of Tylohranchion speciosum, seen from ventral surface ; mag- 
nified (S., 1 inch). 
Fig, 7. Part of branchial sac of Tylohranchion speciosum, seen from the interior ; 
magnified (S., 1 inch). 
Fig. 8. Part of another branchial sac, from interior; magnified (S., 1 inch). 
Fig. 9. Another part of the branchial sac, from interior; magnified (S., 1 inch). 
Fig. 10. Small part of branchial sac ; highly magnified (S., ^ inch). 
Fig. 11. Three ciliated cells, from stigmata; highly magnified (S., ^ inch, enlarged). 
Fig. 12, Part of dorsal edge of branchial sac, showing languets ; magnified (S., 1 inch). 
Fig. 13, Dorsal part of anterior end of Ascidiozooid, showing tentacles, &c.; magnified 
(S., 1 inch). 
Fig. 14. Diagrammatic transverse section of post-abdomen, showing tubules in which 
the reproductive elements are produced ; magnified. 
Fig. 15. Part of germinal tubule, from young Ascidiozooid, showing ova in various 
stages of development ; highly magnified (S., ^ inch). 
Fig. 16, Part of smaller tubules, containing young ova ; highly magnified (S., ^ inch). 
Fig. 17, Tubules from older Ascidiozooid, in which spermatozoa are being produced; 
highly magnified (S., ^ inch). 
