120 Journal of the Asiatic Society of Bengal, —[April, 1905. 
between them and the original ones. When several have been 
produced, the most anterior can be distinguished from the others 
by a dilatation of the alimentary canal which ultimately becomes 
the pharynx of a new individual. The prostomium never takes 
its place as a regular segment in the series, but grows out as a 
lobe on the dorsal surface. The mouth of the young worm is in 
continuity with what will be the new anus of the parent and the 
shells of the food pass to the exterior of the old anus, at the extrem- 
ity of the young individual, until the separation has been com- 
pletely affected. This does not occur until at least 16 new seg- 
ments (in addition to the old extremity) have been formed. The 
clitellum (10th and 11th segments) is already conspicuous, being 
devoid of sete. In adult individuals, however, the glandular struc- 
ture of its integument extends partially over another segment 
on either side. 
O 
EXPLANATION OF PLATE III. 
Fig. Chetogaster bengalensis on a Water-Snail, X 2. 
, 2. Anterior extremity of an adult individual from below, 
showing nerve cords, etc. (Much enlarged). 
p-—prostomium, /.—lower lip, s,—anterior sete, ”.— 
nerve chords, g.—ganglia. 
» 3. Diagram showing arrangement of the sete in a similar 
bundle from the right side. Hach dot represents a seta 
in cross-section. 
, 4. A bundle of setz from the left side of one of the posterior 
segments, seen from behind. (Much enlarged). 
(Text figure.) 
Fig. 1. Young Chetogaster bengalensis just separated by fission 
from its parent. (Somewhat diagrammatic as reyards 
the nephridia). 
p.—prostomium, ph.—pharynx, l.ph.—lumen of _ pha- 
rynx, ©.—cesophagus, c.—clitellum, m.—nephridia, 
p.s.—posterior sucker. 
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