334 
ZOOLOGY OF THE FAR EAST. 
The funnel is often described with a pair of long spirally coiled arms arising from its 
sides. On comparing the fun-iel of these species with that of a species like T. 
neptimi or Bonellia viridis, where it is simple, we find that in species with the spirally 
coiled arms only the lateral margins of the funnel have become very much elongated 
and in the preserved specimens lie in a cork-screw spiral. The structure of the arms 
is exactly like that of the other portions of the funnel and the elongation seems to 
be an arrangement for providing an increased ciliated surface. In stained and 
mounted specimens of the segmental organs, the anterior and posterior borders 
of the funnel lie close together, and the elongated lateral margins lie as the coiled 
arms. The number of coils varies in different species and even in different speci- 
mens. 
Sections near the base of the vesicle (fig. 13) show an internal lining of much 
elongated columnar cells, outside it are two distinct bands of muscle-fibres, which run in 
an oblique direction and are in continuation with the muscles of the body-wall; a 
few connective tissue fibres are also to be seen with the muscle-fibres and there is the 
outermost layer of peritoneal cells {Pe). Sections taken higher up through the vesicles, 
show a regular decrease of the muscle-fibres and the connective tissue, until near the 
tip only a thin layer of connective tissue separates the peritoneal from the inner cells. 
In the inner cells also a regular series from the long columnar to the cubical form can 
be traced from below upwards. The funnels have a lining of ciliated cells, the cilia 
of which work inwards. A transverse section of the spirally- wound arms (fig. 14) 
shows the inner layer of ciliated cells, then a few muscle and connective tissue fibres 
and the outermost layer of peritoneal cells [Pe). 
The contents of these organs were a larger number of coelomic corpuscles and a 
few eggs. They perhaps serve both as nephridia and as the efferent ducts for the 
reproductive elements. 
Aiial vesicles. — These structures like the segmental organs have received different 
names from various authors, some of these are, — -anal vesicles, posterior nephridia, 
anal trees, anal glands, anal gills, etc. The name anal vesicles in the present state of 
our knowledge of their function seems to be the most suitable, and is the one used 
in this paper. 
The structures are very similar in T. dendrorhynchus (fig. 16) and T . hranchio- 
rhynchus, except that they are rather longer in the latter species. I quote here the 
description of the anal vesicles of T. dendrorhynchus from the description of Annandale 
and Kemp (2) . " The anal trees are short and simple, nearly half the length of the body 
in a contracted specimen. They have a slightly brownish tinge and the walls are 
very thin ; the distal extremity is narrowly cylindrical, but the apex is blunt, the 
basal or proximal part is somewhat swollen, but there is no definite vesicle. No 
funnels are visible with the aid of a hand-lens and there are no muscular strands 
attaching the organ to the body-wall. Examined under the microscope, each tree is 
seen to possess two longitudinal rows of ciliated funnels, the mouth of which does not 
exceed 0-047 ^^^^i- in breadth, while the length is not greater than o-t68 mm. The 
two trees open separately into the intestine close to the anus." 
