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SIDNEY F. HARM KB. 
form of a horse-shoe, though the ends of the lophophore 
are not drawn out to the extent found in species with 
numerous tentacles. Twenty-two tentacles can be counted? 
and this was the full number present in this individual. The 
tube (t.) is seen to consist of several superposed cuticular 
layers. 
In the next section shown (PI. 8, fig. 17) the bases of the 
tentacles have become confluent on the anal side, and the lopho- 
phore is now clearly seen to be liippocrepian in form. Some 
indication of the tentacle-vessel can be seen in several of the 
tentacles, in addition to the cavity of the tentacle. The tip 
of the epistome is cut at ep. 
In PI. 8, fig. 18, the union of the tentacle-bases is more 
complete, and a considerable part of the epistome ( ep .) is 
visible. The next figure (PI. 8, fig. 19) shows the epistome 
at its largest part. In PI. 8, fig. 20, the tentacle-bases 
have all united, so that the mouth (m.) is completely out- 
lined. The anus {an.) opens into a depression between a 
lobe of the metasome and the lophophore, and a part of the 
nerve-ring ( n.r .) is visible between it and the mouth. The 
two nephridia are seen in one or two of the sections which 
come next in the series ; but they have not been drawn, as the 
preparations are not very favourable for showing their details. 
In PI. 8, fig. 21, the oesophagus (ass.) and the intestine (int.) 
are seen, as well as the oral part of the nerve-ring ( n . r.). 
The afferent blood-vessel (a. v.) occurs between the oesophagus 
and the intestine, and some of the longitudinal muscles of the 
body-wall are visible. 
PL 8, fig. 22, shows a complete median mesentery ( mes .) 
supporting the two limbs of the alimentary canal ; and both 
the afferent {a.v.) and the efferent (e. v.) blood-vessel. The 
longitudinal muscles of the body-wall are now well developed. 
In PL 8, fig. 23, the longitudinal muscles (Z. m.) are still 
stronger, and about fourteen bundles can be seen on each side 
of the median mesentery. Both the longitudinal blood-vessels 
are still visible. Pl. 8, fig. 24, is through the proximal end 
of the muscular part of the body-wall, and shows part of the 
