86 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
7. rectum. in. tentacle. 
ren. renal vesicles. t.k. terminal knobs on vessels. 
sg. stigmata. tr. transverse vessels. 
sp. testis. t.v. test vessel. 
sph. sphincter. ty. typhlosole. 
st. stomach. v. vessel. 
t. test. v.app. vascular appendage. 
t.c. test cells. v.bl.s. ventral blood sinus. 
Fig. 1. Diagram of the outside of Asczdia, from right side. 
Fig. 2. Transverse section through the atrial aperture 
to show arrangement of internal cavities and 
organs. (To avoid complication the internal 
longitudinal bars are not represented in the 
branchial sac.) 
Fig. 3. A mesh of the branchial sac, diagrammatic. 
A. From the inner surface. B. In section. 
Fig. 4. Diagrammatic dissection to show the structure 
of Ascidia (compare with fig. 2). 
Fig. 5. Section through test and mantle (body-wall) to 
show the relations of the ectoderm and meso- 
derm to the test. 
Fig. 6. Sagittal section through antero-dorsal part of 
body to show relations of nerve ganglion, 
neural gland, &c. 
Fig. 7. Dorsal front of pharynx from inside, to show 
dorsal tubercle, tentacles, and neighbouring 
parts. x 90. 
Puate ILI. 
Figs. 1 to 4 show typical examples of four important 
families of Compound Ascidians, natural size. 
Fig. 1 is a Distomid colony (Colelia). 
Fig. 2 is a Didemnid colony (Leptoclinum). 
Fig. 3 is a Polyclinid colony (Pharyngodictyon). 
rl { 
a ee 
" r . 
ete Bate le ie ee i ee 
