318 



ZOOLOGY. 



to Clymene, having been dredged by the Challenger Expedi- 

 tion at the enormous depth of over three miles (about 5000 

 metres). 



Class IX— ANNULATA. 



Body long, bilaterally symmetrical, cylindrical, consisting ofnuTnerous 

 segments, either unarmed, or m^reuauoMy provided with setm alone or with 

 setcB and paddlelikt appendages (rami). Head simple, with a few simple 

 eyes, or provided with tentacles {antennce) alone, or wibh tentaclesand bran- 

 cIiUB. AneversiMepharynx,armedwithteeth, usually present. Alitnentary 

 system straight, the tubular stomach sometimes sacculated; vent always 

 situated in t/ie last segment of the body. Nermms system weU developed, 

 consisting of a brain and ventrid ganglionated cord. Circ/uZatory system 

 closed, with a dorsal and ventral and lateral vessels connected by anasto- 

 mosing brandies in nearly each segment. A system, of numerous paired 

 segmental organs. Sexes united or separate. Embryo passing through 

 a deavage-stage {morula orblastula), gastrula, sometimes a neurula stage, 

 and after hatching, development is either direct or there is a m,arked met- 

 am,orphosis, the larva passing through a trochospliere and eephalula- 

 stage. 



Order 1. Mirudinea. — Body unarmed, finely segmented ; with, a pos- 

 terior sucker. (Hirudo, Xephelis.) 



Orders. ^re7i«K(fe».— Suborder 1. 0%oc7i<rfa (Xumbricus, Xais). Sub- 

 order 2. — GhMopoda (Arenicola, Syllis, Autolytus, Aphro- 

 dite, PolynoS, Amphitrite, Terebrella, Sabeila, Serpula^ 

 Spirorbis). 



TiBtTLAR TlE-W OP THE CLASSES OP WORMS (VeEMES). 



Anmdata, 



Brachiopoda. 



Polyzoa. 



Snteropneusta. 



Oephyrea. 



Rotatoria. 



Nemertina. 



Nematdminthes. 



Platyhelminthes. 



Vermes. 



