I 
EXPLANATION OF PLATE XI. 
Fig. I. — Seta of T. branchiorhynchus, lateral view. 
„ 2. — Proboscis of T. sabinum, ventral view, x 20. 
„ 3. — Proboscis of T. dendrorhynchus , ventral view. x 3. 
„ 4. — Proboscis of T. branchiorhynchus, ventral view. x 3. 
„ 5. — Transverse section of the proboscis of T. dendrorhynchus, as seen with the 
low power of the microscope. 
6. — Half of a transverse section of the proboscis of T. branchiorhynchus in the 
gill-bearing region; same magnification as in fig. 5. 
7. — Epithelial and other layers on the dorsal surface of the proboscis of T. 
branchiorhynchus as seen with the oil immersion lens. 
„ 8. — Epithelial and other layers on the ventral surface of the proboscis of T. 
branchiorhynchus, same magnification as in fig. 7. 
„ 9. — Wall of the gill-like processes of T. branchiorhynchus, same magnification as 
in fig. 7. 
10. — Dissection of T. sabinum to show the general anatomy ; the mesenteries, 
lateral branches of the nerve-cord, and the blood-vessels not shown. 
II- — Blood-vascular system and fore-gut of T. branchiorhynchus . 
12. — A segmental organ of T. branchiorhynchus as seen in a side view. 
„ 13- — Transverse section of the vesicle of segmental organ of T. branchiorhynchus 
near the external opening. 
„ 14- — Transverse section through one of the spiral prolongations of the funnel of 
T. branchiorhynchus. 
„ 15. — Anal vesicles of T. sabinum. 
,, 15a. — One of the funnels of the anal vesicle of T. sabinum. x 250. 
„ 16. — Anal vesicle of T. branchiorhynchus showing the relation with the rectum. 
REFERENCE LETTERING. 
A.V., Anal vesicle. Ca., Caecum. C i., Outer layer of the cuticle. C.n., Inner layer of the cuticle. 
C.e., Ciliated epithelium. C.g., Ciliated groove of the mid-gut. Cm., Circular muscles. Cr., Crop. C.t., 
Connective tissue. Czi., Cutis. D.i'., Dorsal blood-vessel, f.c, Columnar epithelium. G., Gizzard. Gi., 
Gills. G.c, Gland cells. H., Heart. La., Lacunar spaces in the proboscis. L.m., Longitudinal 
muscles. L.v., Lateral blood-vessel. M.r., Muscle ring. N.c, Nerve cord. N.cL, Nerve cell. N.I., 
Lateral nerve of the proboscis. N.v., Neuro-intestinal loop of the blood-vessels in the region of the 
pre-intestinal constriction. Oe., Oesophagus. P , Pharynx. Peritoneal layer of cells. JR., Rectum. 
S., Setal end seen from within. Si., Siphon. S.o., Segmental organ. T'., Vesicle of the segmental organ. 
V.V., Ventral vessel. 
