CLASSIFICATION. 63 



Sub-Kingdom 3,—MOLLUSGA. 

 Siipra-elass 1. Phanerogama Latr. (Mouotocardia, Miirch). 

 Class 1. ANDROGYNA (Hevmaphrodlta, Latr.). 



Order 1. (jEOphila, Fer. (Stylommatophora, A. Schmidt). 



Phyllovora with jaw. Agnatha without jaw. 

 Order 2. Hygrophila ; eyes at the interior ])ase of the 

 tentacles. Planorbis. Physa, Limnjea, Siphonaria, An- 

 cylus, Auricula. 

 Order 3. Tectibranchia (Pomatobranchia), Pyramidella 

 (connecting with the preceding genus), Obeliscns, Odos- 

 tomia, Chemnitzia, Actaeon, Bulla, Aplysia, Notarchus. 

 Gasteropteron connecting with the Pteropods. 

 Order 4. Pteropoda. 



1. Gymnosomata. Clione, Pneumodei-mon. 

 '1. Ihecosomata. Clio, Hyalsea, Liraaeina, Heterofusus. 

 Older 5. Gymnobranchia. 



1 . Pygohranchia. Doris, etc. ; branchijt^ near the anus. 



2. Pleurognatha.* Pleurophyllidia. Dendronotus, Trito- 

 nia, Bornella, ^olis, Glaucus, Phyllirhoe. 



Order 6. Pellibranchia. Tethys, ChioriBa, Hermiva. Ely- 

 sia, Limapontia, Pelta. 

 All these mollusks are placed at the head of the gasteropods 

 by Cuvier. Messrs. Troschel and Gray arrange them between 

 the Acephala and Patella, considering androgynism as probably 

 a character of absolute inferioritA' ; but the Acephala have gen- 

 erally separated sexes. 



Class II. DIOICA, Latr. (Exophallia, Morch). 



Order 1. T^nioglossata, Troschel. 

 This is the only division where the famil}^ groups and their 

 reciprocal relations do not appear to Miirch to be perfectly clear. 

 In any case, it appears incontestable that all mollusks having 

 seven ranges of teeth form a characteristic group. Recently, 

 Troschel has divided the Tienioglossata into three groups accord- 

 ing to the trunk : 



* Dr. Mobiiis has recently shown that the Doridie have also lateral jaws, 

 although very little developed. 



