224 THE CEPnALOPIIORA. '§> 201 . 



Family : Sagittina. 

 Genus : Sagitta. 



Family Hyaleacea. 



Genera : Hyalea, Cleodora, Cijmbjtlin, Tiedemannia, Cuvieria, Creseis, 



Liinacina. 



Familv : Clioidea. 

 Genera : Clio, Pneumodermnn, Spoiigiohranchaea. 



ORDER 11. HETEROPODA. 



Animals whose locomotion is performed by a carinated natatory appara- 

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



Genera : Phjllirrhoc, 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, Pelta, Actaeon, Actaeonia, Lissosoma, Chalidis, Flabd- 



lina, Zephyrina, Aniphorma. 



Family: Angiopiiora. 



Genera: Tergipes, Venilia [Proctonotiis), CalUopoea, Eolidina, Aeolh 



{Eolidia). 



SUB-ORDER U. HETEROBRANCHIA. 



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

 body. Sometimes there is a very simple patelliform shell. 



Family : Nudibranciiia. 



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



Family : Inferobranchia. 



Genera : Diphyllidia, Phyllidia, Ancyliis. 



Family : CYCLOBRANCniA. 

 Genera : Patella, Chiton. 



Family : Scutibranchia. 

 Genera : Haliotis, Fissurella, Emarginula. 



