174 ZOOLOGY. 
feet are jointed, thus anticipating the jointed appendages of 
the Crustacea and Insects. 
The Annelides are divided into two suborders. The first 
suborder, Oligocheta, comprises Lumbricus, Nats, etc., while 
the second suborder, Chetopoda, embraces Syliis, Autolytus, 
Nereis, Polydora, Aphrodite, and Polynoé, which are free- 
swimming, while the tubicolous worms which respire by spe- 
Fre, 122, 
Fig. 122.—Cistenides Gouldii, and its tube.—After Verrill. 
Fig. 123.—Euchone elegans, enlarged.—After Verrill, 
cial branchiz, or gills, on the head, live in tubes of sand or 
in limestone shells. ‘I'hose which live in sand or mud-tubes 
are Cirratulus (Fig. 124), Clymene and Clymenella (Fig. 120), 
which has no branchie, Amphitrite (Fig. 121), Teredrella, 
Cistenides (Fig. 122), Sabella, and Buchone (Fig. 123), 
while Protula, Filograna, Serpula, and Spirorbis secrete 
more or less coiled limestone tubes. The large solid shelis 
of the Serpule assist materially in building up coral reefs, 
