52 



Bibliographical Notices, 



supra dilatatum, infra angustatum ; mandibula3 angulus rotun- 

 datus, dentes primores inferiores acuminati. 

 a. Molares f . 

 Hydromys. 



b. 



Molares §. 



a. M.tuberculati. ft. M.plani, opposite y. M.alternatira incisi. 



Mus. 



Cricetus. 



Dendromys. 



Akodon. 



Hapalotis. 



Pseudomys. 



Mystromys. 



Rhombomys. 



Psammomys. 



Meriones. 



Euryotis. 



c. Molares %. 

 Sminthus. 



d. Molares |. 



i fSigmodon. 



g I Neotoma. 



bX) 



^ Elimodon. 

 Reithrodon. 

 bo [_Ctenodactyh 



4! f My odes. 

 '"p < Hypudaus. 

 •£ [Fiber. 



a. M. tuberculati. 

 Per ognat hits*. 

 Distributed over the whole earth. 



M. plani, incisi. 

 Saccomys. 



IX. Castorina. Corpus robustum, magnum, pedes 5-dactyli, pos- 

 teriores palmati ; dentes primores validi, cestiformes, molares J 

 complicate latere altero triplicate altero implicati. 



Castor, Myopotamus. 



Geog. distr. Northern & temperate districts of Old & New World. 



Myopotamus belongs to the southern half of South America. 



X. Hystricina. Corpus aculeis teretibus validis, setis intermixtis 



vestitum; foramen infraorbitale maximum; clavicular incompletae; 

 dentes molares | complicati. 



a. Philogsea. ft. Philodendra. 



Hystrix. Erethizon. 



Atherura. Cercolabes. 



(Synetheres and Sphiggurus.) 

 Southern Europe, Asia, Africa and America. 



XI. Subungulata. Corpus pilis tectum, cauda brevissima aut nulla, 

 ungues subungulaeformes, foramen infraorbitale permagnum, 

 clavicular incompletae, dentes molares J. 



a. Molares complicati. b. Molares compositi. 



Dasyproct-a. Hydrochcerus. 



Coslogenys. Cavia. 



Confined to South America. Kerodon. 



XII. Dtjplicidentata. Dentes primores superiores duplicati, foramen 

 infraorbitale parvum, foramina optica conjuncta, palatum osseum 

 singulariter coarctatum, clavicular partim incompletae, partim 

 completae. 



Lepus, Lagomys. 



Distributed over the whole earth with the exception of NewHolland. 



* Dipodomys, Gray (see vol. vii. p. 521), will perhaps be placed here. 



