84 ^rr. O. Thomas on Australian Rats 



Skull very imich as in Mus Uneolatus. lliiul feet normal, 

 ■with the. usual six pads. 



Species : C. apiculis and murinus. 



Tlie tjradation of this genus, from C. apicaUs, throuo-li 

 C. murinus, Mus Uneolatus, and Mus lllgginsi, into true Mas, 

 atibrds an interesting study in evolution. Whetlier the Mus 

 h'neolatus group should not also be subgenerically sei>arated 

 from tiie ordinary sjjecies of Mas is a question which may 

 have to bo considered later. 



III. Ammomys. 



Genus novum Type : A. hirsufii^, Goukl. 



Teeth as figured in Mus argurus ; a distinct and well- 

 defined postero-internal cusp on each molar, so that along the 

 inner edge of the full molar series there are 8-9 cusps. 

 Skull rat-like in general form, a well-developed coronoid 

 process on the mandible. Hind feet normal, with six pads. 

 MammaB, so far as known, 0—2 = 4. 



Species : A. hirsutus, viacrurus, pedunculatus, and argurus. 



IV. CONILURUS. rp 



Hapaloiis, Lieht. Darst. Siiug. text to pi. xxix. 



(1829) (nee Hiibner, 1816) C. albipes, Licht. 



Conilurits, Ogilb. Tr. Linn. Soc. xviii. p. 124 (1838). C. albipes, Licht. 



Teeth and foot-structure as in Ammomys. Skull highly 

 modified, broad, flattened, the interorbital region concave, the 

 palatal foramina enlarged, and the mandibular coronoid 

 process and incisive capsule reduced or absent. 



Species: C. albipes and penicillatus. 



Uf the other species described as members of this group, 

 arhoricola, Krefft, is a Musrattus; personatus, Krelft, also 

 probably belongs to Mus ; and caudimaculataj KrefFt, and 

 pnpuanus, Ramsay, to Uromys. 



With regard to the development and evolution of the 

 additional postero-internal cusp on the molars, Dr. Winge, 

 our greatest authority on the subject, when treating* of its 

 presence in Micromys, has considered that it is a new develop- 

 ment, the two original internal cusps (numbered by him on his 

 general scheme " 6 '' and " 7 ") having been pushed forward 



• " Graeske Pattedjr," Vid. Medd. For. Copenhagen, 1881, p. 17 (under 

 " Mus myst(iclnus'), and 1882, pi. iii. fig. 10. 



