134 MOLLUSCA. 
THE SIXTH CLASS OF THE MOLLUSCA. 
CIRRHOPODA. 
LeEpAS and TRITON, Lin. 
THE cirrhopoda, in several points of view, are intermediate be- 
tween this division and that of the articulata: enveloped by a 
mantle and testaceous pieces which frequently resemble those 
seen in several of the acephala, their mouths are furnished with 
lateral jaws, and the abdomen with filaments named cirri, 
arranged in pairs, composed of a multitude of little ciliated arti- 
culations, and corresponding to a sort of feet or fins, similar to 
those observed under the tail of several of the crustacea; their 
heart is situated in the dorsal region, and the gills on the sides; 
the nervous system forms a series of ganglions in the lower part 
of the abdomen. ‘These cirri, however, may be considered as 
analogous to the articulated appendages of certain species of 
teredo; while the ganglions, in some respects, are mere repe- 
titions of the posterior ganglion of the bivalves. ‘The position 
of these animals in the shell is such, that the mouth is at the 
bottom, and the cirri near the orifice. Between the last two 
cirri is a long fleshy tube, that has sometimes, but erroneously, 
been taken for their proboscis, and at the base of which, near 
the back, is the opening of the anus. Internally, we observe 
a stomach, inflated by a multitude of small cavities in its 
parietes, which appear to fulfil the functions of a liver, a sim- 
ple intestine, a double ovary, and a double serpentine oviduct, 
supplying from its walls the prolific fluid, and prolonged 
through the fleshy tube to open at its extremity. These ani- 
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