A CONTRIBUTION TO THE ANNELIDA. 61 
upper arch again has transverse muscular fibres close to the 
hypodermic border. A powerful muscular mass exists above, 
ending in the thin hypodermic and dense cuticular layers 
bounding the floor of the upper canal (Pl. 7, fig. 3). The 
opposite or upper face of the canal has a very thin cuticular 
coat and a thick glandular (hypodermic) layer. Folds or 
ridges next appear at the sides (Pl. 6, fig. 7, e) where the 
dorsal arch joins the muscular stem of the proboscis, and they 
pass dorsalwards on this arch in the form of an extended ridge 
on each side in transverse section, the surface being hypo- 
dermic, while beneath is areolated glandular tissue. Proceed- 
ing backward these lateral ridges increase in size, and instead 
of an even surface show prominent ridges, while by-and-by a 
belt of this folded tissue passes entirely across the upper 
chamber. Inferiorly the stem of the proboscis now presents a 
somewhat regularly interwoven field of cross-fibres like mesh- 
work, bounded ventrally by a rim of longitudinal fibres, the 
upper edge being defined by a cuticular investment. Beyond 
the longitudinal belt at the ventral border of the decussating 
fibres is a broad belt of vertical fibres. 
The chamber soon shows a regular series of transverse ridges 
of hypodermic glandular tissue, and then terminates in the intes- 
tine. Externally is a layer of longitudinal fibres, internally a 
coat of circular fibres, and the glandular lining has cilia on its 
surface. 
In longitudinal section (Pl. 6, fig. 7) the mouth has various 
prominent folds of the lining membrane in front, but the ante- 
rior region of the proboscis in this species did not present the 
regular series of papillz indicated in the figure of Professor 
Ehlers. The main channel passes dorsally, and reaches the 
thin-walled chamber marked ds. in fig. 7, Pl. 6. The dorsal 
wall agrees with that shown in Pl. 7, fig. 3, though the cuti- 
cular layer is less marked, and extends to the opening into the 
intestine. In this chamber the ventral surface is formed by 
a portion with bold ridges (r., fig. 7, Pl. 6, where a part only 
is shown, as the section is not median). In the ordinary or 
retracted condition of the parts the food would thus be acted 
