PLATE XVIII. 
Figs. 1-6. Distaplia vallii, n. sp. 
Figs. 7-14. Symplegma viride, n. sp. 
at. 
hr. 
h.p.c. 
cce. 
d.l. 
d.t. 
en. 
i. 
i.l. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Atrial aperture. 
Branchial aperture. 
Black pigment cell. 
CiBcum. 
Dorsal lamina. 
Dorsal tubercle. 
Endostyle. 
Intestine. 
Internal longitudinal bar of bran- 
chial sac. 
l.v. Fine longitudinal vessels of bran- 
chial sac. 
m. Mantle. 
CB. CEsophagus. 
p.c. Mass of pigment cells. 
p.p. Peripharyngeal band. 
r. Eectum. 
r.p. c. Eed pigment cell 
sg. Stigmata of branchial sac. 
sph. Sphincter. 
st. Stomach. 
t.c. Test ceEs. 
t.k. Terminal bulb on vessel in test. 
t.m. Test matrix. 
tr. Transverse vessel of branchial sac. 
V. Yessel in test. 
v.ap. Vascular appendage. 
z. Prebrancbial zone. 
1. Colony of Distaplia vallii, from Station 212 ; natural size. 
2. Colony of Distaplia vallii, from Mediterranean ; natural size. 
3. Ascidiozooid of Distaplia rosea, from Naples ; magnified (S., 1 inch). 
4. Section through test of Distaplia vallii; highly magnified (S., ^ inch). 
5. Part of mantle of Distaplia vallii, from Mediterranean, showing pigmentation ; 
magnified (S,, 1 inch). 
6. Part of branchial sac of Distaplia vallii ; highly magnified (S., ^ inch). 
7. Colony of Symplegma viride ; natural size. 
8. Part of test of Symplegma viride, showing vessels ; highly magnified (S., inch). 
9. Part of outer layer of test of Symplegma viride, showing network of vessels ; 
magnified (S., 1 inch). 
10. Part of branchial sac of Symplegma viride; magnified (S., 1 inch). 
11. Small part of another branchial sac of Symplegma viride; magnified (S., 1 inch). 
12. Part of branchial sac of young Ascidiozooid of Symplegma viride, showing internal 
longitudinal bars ; highly magnified (S., ^ inch). 
1 3. Dorsal part of anterior end of Ascidiozooid of Symplegma viride, showing dorsal 
lamina, &c.; tentacles not represented; highly magnified (S., inch). 
Fig. 14. Alimentary canal of Symplegma viride; magnified (S., 1 inch). 
