21 



margin and three times on the inner ; in the second molar the enamel 

 is indented once on the outer margin and twice on the inner ; and 

 in the last molar once on the outer, and twice on the inner. Fur 

 long and soft. Tail moderate, well clothed with hair. Claws long, 

 but slightly curved and formed for burrowing. Fore-feet mode- 

 rately large. Thumb furnished with a distinct claw. Ears moderate, 

 well clothed with hairs. 



Species Mus {Scapteromys) tumidus. 



Subgenus 2. Oxymycterus*. 



Molars with the folds of enamel penetrating deeply into the body 

 of the tooth. Front molar of the lower jaw with three indentations on 

 the inner side and two on the outer ; second molar with two on the 

 outer side and the same number on the inner ; the last molar with 

 one indentation of the enamel on each side. Fur long and soft. 

 Claws long, but slightly cui'ved, and formed for burrowing. A di- 

 stinct claw on the thumb. Tail short, moderately furnished with 

 hair. Nose much elongated and pointed. 



Species Mus {Oxymycterus) nasutus. 



Subgenus 3. ABROTHRixf. 

 Folds of enamel penetrating deeply into the sides of the molars. 

 The front molar of the lower jaw has three folds of enamel on the 

 inner side and two on the outer ; the second molar has two on the 

 inner side and one on the outer ; and the last molar has one on each 

 side. Fur long and soft. Tail short, well furnished with hair. 

 Thumb with a short rounded nail. Ears well furnished with hair. 



Type Mus {Abrothrix) longipilis. 



Species 2 Mus {Ab.) ohscurus. 



3 olivaceus. 



4 . — micropus. 



5 brachyotis. 



6 ~ xanthorhinus. 



7 canesce7is. 



8 arenicola. 



In general appearance these animals resemble ArvicolcB. 



Subgenus 4. CalomysJ. 

 Fur moderate, soft. Tarsus almost entirely clothed beneath with 

 hair. Front molar ^vith three indentations of enamel on the inner 

 side and two on the outer ; second molar with two on the inner 

 and two on the outer ; and the last molar with one on each side. 

 Type Mus (Calomys) bimaculatus. 

 Species 2 3Ius {Cal.) elegans. 



3 • gracilipes. 



Mus maurus and M. brevirostris I regard as belonging to the re- 

 stricted genus Mus. In Mus Jtavescens the dentition diilcrs slightly 

 ' from that of the ordinary mice. 



* Oxymycterus, from O^nf, sliar{5, and M^xtijj, nose. 

 t Abrothrix, from ' A,6joc, soft ov delicate, and 0f /f , hair. 

 X Calomys, from KaAoj, beautiful, and Mv?. 



