THE CH^TOGNATHA, OE PEIMITIVE MOLLUSCA. 379 



A Archi-Mollusc. 



9 OCTOPODA, 



Ovd 



B. Ch/ETocnatha 



0. Nautilus. 

 . O ; o I 



F. POLYPLACOPHORA- 



Text-fig. 10. — Body cavities. 



The doited Hue represents the ccelomic epithelium, pc. Pericardial 



coeloui ; ffc. Perigouadial cceloni. 



