CLASSIFICATION. 63 



Sub-Kingdom 3,MOLLUSCA. 



Supra-class 1. PHANEROGAM A Latr. (Monotocardia, Morch). 

 Class 1. ANDROGYNA (Hermaphrodita, Latr.). 



Order 1. GEOPHILA, Fer. (Stylomraatophora, A. Schmidt). 



Phyllovora with jaw. Agnatha without jaw. 

 Order 2. HYGROPHILA ; eyes at the interior base of the 

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

 cylus, Auricula. 



Order 3. TECTIBRANCHIA (Pomatobranchia), Pyramidella 

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

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

 Gasteropteron connecting with the Pteropods. 

 Order 4. PTEROPODA. 



1. Gymnosomata. Clione, Pneumodermon. 



2. Ihecosomata. Clio, Hyalrea, Limacina, Heterofusus. 

 Order 5. GYMNOBRANCHIA. 



1. Pygobrancliia. Doris, etc. ; branchite near the anus. 



2. Pleurognatha.* Pleurophyllidia. Dendronotus, Trito- 

 nia, Bornella, ^Eolis, Glaucus, Phyllirhoe. 



Order 6. PELLIBRANCHIA. Tethys, Chioiwa, Herman, 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 inferiority ; 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 famity groups and their 

 reciprocal relations do not appear to Morch 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 Trenioglossata into three groups accord- 

 ing to the trunk : 



* Dr. Mobius has recently shown that the Doridae have also lateral jaws, 

 although very little developed. 



