224 THE CEPHALOPHORA. §201. 



Family : Sagittina. 

 Genus : Sagitta. 



Family Hyaleacea. 



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



LimaciTia. 



Family : Clioidea. 

 Genera : Clio, Pneumoderynon, Spoiigiobranchaea. 



ORDER II. HETEROPODA. 



Animals whose locomotion is j^erformed by a carinated natatory appara- 

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



Genera : PhyUirrhoc, Pterotrackea, Carinaria, Atlanta. 



ORDER in. 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, Ckalidis, Flabel- 

 lina, Zepkyrina, Amphorina. 



Family : Angiopiiora. 



Genera: Tergipes, Venilia [Procto7iotus), Calliopoea, Eolidina, Aeolis 



{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: Nudibranchia. 



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



Family : Inferobranchia. 



Genera : Dipkyllidia, Phyllidia, Ancyliis. 



Family : CYCLOBRANcniA. 



Genera : Patella, Chiton. 



Family : Scutibranchia. 



Genera : Haliotis, FissnreUa, Emarginula. 



