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organs termed cirri (fig. 9). These out-growths, or para- 
podia, are locomotor organs, and, by their active move- 
ment in the living animal, enable it to creep or swim as 
occasion demands. fach parapodium consists of a basal 
piece from which extend outwards two almost equal, 
usually bilobed, processes, a dorsal one (the notopodium ), 
and a ventral one (the neuropodium). In each of these 
two vami of the parapodium there is a large setal sac, 
formed by invagination of the epidermis, the lips of which 
are well seen in Vere?s. From the inner end or bottom 
of this sac the sete arise, each being formed by products 
from a single cell. The bundle of setee contained in each 
sac may be protruded o1 retracted or moved in various 
directions by means of a number of slender muscle bands 
inserted into the bottom of the sac. In addition to these 
sete, which may project a considerable distance beyond 
the lips of the setal sac, there is in each notopodium and 
neuropodium a stouter, dark-coloured, needle-shaped aci- 
culum of a similar constitution to the sete. Its base 
extends further inwards than the bases of the ordinary 
sete, but its pointed tip projects only a short distance 
beyond the surface of the parapodium. The two acicula 
serve as an internal skeleton to the parapodium, and to 
them the museles which move the bundles of setze are 
attached. On the dorsal side of the notopodium, and on 
the ventral side of the neuropodium, is a finger-shaped, 
or filamentous sensory process, or cirrus. 
The head or prostomium of WVere?s (figs. 7 and 8) is 
pre-oral. It is tollowed by the peristomium on the 
antero-ventral surface of which the mouth is situated. 
The prostomium bears on its dorsal surface two pairs of 
eyes, in front a pair of short sensory tentacles and ventro- 
laterally a pair of much stouter sensory and muscular 
palps. The peristomium, which bears some resemblance 
