$ 201. THE CEPHALOPHORA. 225 
Famity: TEctrpraNncntia. 
Genera: Gasteropteron, Umbrella, Doridium, Bulla, Bullaea, Aplysia, 
Notarchus, Dolabella, Pleurobranchus, Pleurobranchaea. 
SUB-ORDER UI. TUBICOLAE. 
Animals which are enclosed, together with their branchiae, in simple 
slightly curved or irregularly flexuous tubes. 
Faminy: CrrripRaNcata. 
Genus: Dentalium. 
Famity: Tosustprancuta. 
Genera: Vermetus, Magilus. 
SUB-ORDER IV. PECTINIBRANCHIA. 
Branchiae in a special cavity situated at the anterior part of the back. 
Shell regularly spiral. 
Famity: SiGarerina. 
Genus: Sigaretus. 
Famity: Pourpurirera. 
Genera: Buccinum, Harpa, Cassis, Purpura, Eburnea, Terebra. 
Famity: CANALIFERA. 
Genera: Murex, Struthiolaria, Tritonium, Turbinella, Fasciolaria. 
Famity: Awata. 
Genera: Strombus, Rostellaria, Pterocera. 
Famity: QCrriviracea. 
Genus: Cerithium. 
Famity: VoLuracea. 
Genera: Voluta, Oliva, Mitra. 
Fammy: Invouvra. 
Genera: Cypraea, Ovula. 
Famity: Conorpga. 
Genus: Conus. 
Famity: Trocuorpea, 
Genera: Scalaria, Turbo, Trochus, Phasianglla, Rotella, Littorina, Jane 
thina. 
Famity: Nerrracea. 
Genera: Natica, Nerita, 
