28 



ternally in each. In the front molar of the lower jaw the enamel 

 enters the body of the tooth three times internally, and twice ex- 

 ternally. 



As the above-mentioned characters, in Mr. Waterhouse's opinion, 

 evidently indicated an aberrant form of the Muridae, he suggested 

 the propriety of constituting a subgenus under the name of Fhyllo- 

 tis* for the reception of the species. 



They were characterized as follows :— 



Mus (Phyllotis) Darwinii, 31. siiprd pilis cinnamomeis et ni- 

 grescentihus inter mixtis ; ante oculos cinerascentibus ; genis, 

 lateribus corporis, et caudd piope basin, fulvo-cinnamonieis ; 

 partibus hiferioribus pedibusque albis ; cturibus pcrmagnis,fere 

 nudis ; caudd caput corpusqm fere ceqitante, supra fusco-nigri- 

 cante, subtits albd. 



unc. lin. 

 Longitndo ab apice rostri usque ad cauda; basin 6 



caudce 4 9 



ab apice rostri ad marginem oculi . 8^ 



ab apice rostri ad basin auris . . , . 1 a\ 



tarsi digitorumque I 1^ 



auris 11| 



Auris latitudo llj 



Hab. Coquimbo. 



This little animal is remarkable for its large leaf-like ears. 



Mus (Phyllotis) xanthopygus. M. supra pallide brunncus 

 jlavo-lavatus, ad latera flavescens, subtus albus ; capite gris- 

 cescente ; natibus Jiavis ; pedibus albis ; auribus majusculis 

 pilis albis et Jiavis intermixtis obsitis ; caudd longitudineni cor- 

 poris fere cequante, supra nigricante ; subtiis alhd ; rellcre 

 longo et molli ; pilis corporis omnibus ad basin plumbeis ; 

 mystacibus perlongis albescentihus, ad basin nigris. 



unc. lin. 

 Longitudo ab apice rostri ad caudse basin . . 5 3 



caudce' 3 10 



ab apice rostri ad marginem oculi . 6| 



ab apice rostri ad basin auris .... 1 3 



tarsi digitorumque 1 1 



auris 7 



Auris latitudo 6^ 



Hab. Santa Cruz. 



'2 



Mus (Phyllotis) griseo-flavus. M. supra griseus jlavo-lava- 

 tus, ad latera jlavus, subtus albus ; pedibus albis ; auribus 

 magnis et fere nudis ; caudd caput corpusque fere (cqiuinte, 

 supra fusco-nigricante, subtiis albd ; vellere longo, molli ; pilis 

 ad buses plumbeis. 



* Phi/llolis, from $t/XXo», a leaf, and Oi/j, coro;, an ear. 



