224 THE CEPHALOPHORA. <§.20K 



Family : Sagittina. 

 Genus : Sagitta. 



Family Hyaleacea. 



Genera : Hijalea, Cleodora, Cymhdia, Tiedeinannia, Cuvieria, Creseisy 



Limaciiia. 



Family : Clioidea. 

 Genera : Clio, Pneumoder mo7i, Spongiobranchaea. 



ORDER II. HETEROPODA. 



Animals whose locomotion is performed by a carinated natatory appara- 

 tus situated under the abdomen and provided often with a sucker. 



Genera : Phyllirrhoe, Pterotrachea, Carinaria, Atlanta. 



ORDER III GASTEROPODA. 



Animals which creep by means of a muscular disc situated under the 

 body. 



SUB-ORDER I. APNEUSTA. 



Without distinct respiratory organs, and without a shell. 



Family: Anangia. 



Genera : Rhodope, Pelf a, Actaeon, Actaeonia, Lissosoma, Chalidis, Flabel- 

 lina, Zephyrina, Amphorina. 



Family: Angiophora, 



Genera : Tergipes, Venilia [Proctonotus), Calliopoea, Eolidina, Aeolis 



[Eolidiaj. 



SUB-ORDER II. HETEROBRANCHIA. 



The branchiae inserted more or less freely upon various parts of ths 

 body. Sometimes there is a very simple patelliform shell. 



Family : Nudibranchia. 



Genera : Scyllaea, Tritonia, Thetis, Doris, Polycera, Plocamophorus, 



Family : Inferobranchia. 



Genera : Dipkyllidia, Phyllidia, Ancylus. 



Family : Cyclobranciiia. 



Genera : Patella, Chiton. 



Family : Scutibranciiia. 



G enera : Haliotis, Fissurella, Emarginula. 



