236 



ZOOLOGY. 



feet are jointed, thus anticipating the jointed appendages of 

 the Crustacea and Insects. 



Tlie Annelides are divided into two suborders. The first 

 snboi-dev, OUcfochmta, comprises Lumbricics, Nais, etc., while 

 the second suborder, Chmtopoda, embraces Syllis, Autolycus, 

 Nereis, Polydora, Aphrodite, and Polytwe, which are free- 

 swimming, while the tubiculons worms which respire by spe- 



FiG. 158. 



Fig. 158, — Cistenides Gouldii^ and its tnbe. — After Verrill. 

 Fig. 159,— .E'wc/itme elegans, enlarged, — Alter Verrill. 



FiQ, 159. 



cial branchiae, or gills, on the head, live in tubes of sand or 

 in limestone shells. Those which live in sand or mud-tubes 

 are Cirratiilus (Fig. 160), Clymene axid Clymenella (Fig. 156), 

 which has no branchiae, Amphitrite (Fig. 157), TerelreUa, 

 Cistenides (Fig. 158), Sabella, and Euchone (Fig. 159), 

 while Protula, Pilograna, Serpula and Spirorbis secrete 

 more or less coiled limestone tubes. The large solid shells 

 of the Serjjulaj assist materially in building up coral reefs, 



