GOG On Australian Mi(riiies hitherto referred to '" Mus/' 



Legqadina. Mesopterygoid fossa broad in front, narrowing 

 backwards. 



Molars higb, with heavy cusps, more or less resembling 

 those of Leporillus. No antero-internal secondary cingular 

 cusp on ni (except as an unusual abnormality). 

 Type. Ps. australis, Gray. 

 Other species : — 



Ps. avritiis, sp. n. (see succeeding paper). 



Ps. hic/gmsi, Trouess. 



Ps. lineolatusy Gould. 



Ps. murinus, Gould* (probably =:auslraUs). 



Ps. shortridgei, Thos. 



2. Thetomts, subg. n. 



Size medium. Form of skull more normal, but the 

 anterior plate of zygoma still concave in front. Palatal 

 foramina fairly long, but not widely open. Pterygoid region 

 normally murine. 



Molars fairly normal, but a distinct antero-internal cingular 

 cusp present on m^. j\lolar laminae not specially tilted up. 

 Type. Pseudomys [Thetomys) nanus {AIus nanus^ Gould). 

 Other species : — 



Ps. ferculinus, Thos. 



Ps. gouldiy Gray. 



Ps. gracilicauda, Gould, 



Ps, prceconis, sp. n. (see succeeding paper). 



3. Leggadixa, subg. n. 



Size small. Form of skull normal. Anterior zygomatic 

 plate straight or convex in front as in ordinary murines. 

 Palatal foramina nariow. Pterygoid region peculiar, the 

 parapterygoid fossae broad and very shallow, scarcely hollowed 

 at all, the ectopterygoids bordering it externally low, flat, 

 not or scarcely raised up above the level of its floor ; ento- 

 pterygoids also much lower and less projecting than usual. 



Molars very variable, but always witii a well-marked 

 antero-internal cingular cusp on m^. In P. delicatulus this 

 is small, in herniannshurgensis intermediate, and in forrei>ti 



* In my paper of 1906, " On the Generic An-angement of the Australian 

 Hats hitherto referred to Conil^irus," this species, following Gould, was 

 ern)neouslv united -with " C. apicalis " in the new genus Leporillus, 

 apicalis being chosen as the type. As a result of this mistake, the generic 

 description of LejJonllus is not altogether applicable, and (an accidental 

 lapsus calami being also corrected) may run as follows : — Molars, as in 

 Hotomys, without postero-internal cusps. Skull very much as in 

 Conilurus. Hind feet normal, with the usual six pads. 



