SYNOPSIS' OF THE MURIDiE OF NORTH AMERICA. 



Family MURID^. 



Taken in its current acceptation, but witli exclusion of the 

 genus Jacuhis, which differs sufficiently' in dentition, in the cha- 

 racter of the anteorbital foramen, proportions of limbs, and other 

 features. 



1.1—1 . c. 0=0 0-0 3-3 _ 4-4 _ 8 _ ^^ ^^^^^^ 



1—1 0-0 0—0 ' 3—3 4—4 8 



Anteorbital foramen a large pyriform slit, bounded exteriorly by 

 a broad plate of the maxillary'. 



Subfamily Murine. 



Molars rooted, tubercular, with crenate peripher}'. Root of 

 under incisor causing protuberance on outside of jaw, at or near 

 notch between cond^de and coronoid process. Descending pro- 

 cess of mandible a broad flattened plate, wholl}^ below plane of 

 the molars. Anterior root of zygoma deeply nicked at the ante- 

 orbital foramen. Palate nearl}' plane. 



Murine Series. 



Molars with three tubercles in transverse series. Soles naked. 

 (Onl}^ indigenous in the Old World — introduced in the New.) 



Genus I. MTJS, Linn., emend. 



1. Mus decumauus. 



2. Mus alexandrinus. 



3. Mus rattus. 



4. Mus musculus. 



' Abstract of a memoir in which the character.s of the varieties, species, 

 and higher groups are treated in full, Avith synonymy, bibliograpliy, etc., 

 and the argument for the vieAvs advanced. Based on the material (several 

 thousand specimens) in the Museum of the Smithsonian Institution. 



