68 
ZOOLOGY OF THE VOYAGE OF THE BEAGLE. 
sides of the body, white ; hairs of the back palish gray at the base, those of 
the belly indistinctly tinted with very pale gray at the roots ; ears and 
moustaches pale brown. 
Habitat, New South Wales. 
This species is about half-way between Mus Rattus and Musmusculus in size, 
and is remarkable for its delicate colouring. The molar teeth are figured in Plate 
34; fig. 18. a , represents the molars of the upper jaw, and fig. 18. b, those of the 
lower. 
Genus— REITHRODON.* 
Rentes primores | ; inferioribus acutis, gracilibus, et antice Icevibus ; superiorities 
gracilibus , anticb longitudinalitbr sulcatis. 
Molares ulrinque f radicati ; primo max imo, ultimo minima: primo superiore plicas 
vitreas duas extern l et interne alternation exhibente ; secundo, et tertio, plicas duas 
externe, interne unam : primo inferior e plicas vitreas tres extern duas interne ; 
secundo , plicas duas ext erne, unam interne ; tertio unam externb et inter rd, exhi- 
bentibus. 
Artus incequales : antipedes A-dactyli, cum pollice exiguo : pedes postici 5-dactyli , 
digitis externis et internis brevissimis. 
Ungues parvuli et debiles. Tarsi subtiis pilosi. 
Cauda mediocris, pilis brevibus adpressis instructa. 
Caput magnum, f route convexo : oculis magnis : auribus mediocribus. 
The present genus according to my views belongs to the family Muridce. The 
modifications of structure which have led me to separate it from the genus Mus 
are as follows : 
External characters. — The most conspicuous points of distinction between the 
external characters of Reitlirodon and Mus (if we regard M. rattus, M. decu- 
manus or M. musculus as typical examples of that genus,) consist in the arched 
form of the head, the large size of the eyes, the stout form of the body, and 
the upper incisors being grooved. The ears, tail and feet are more densely 
P«0poe, a channel ; OSov, a tooth. 
