20 



stincte obsitis, illis internis auratis; camhl capitem corpusque 

 fere ccquantcinlis puree tectd; sujird, obscure fused, subtiis pal- 

 lide fused; pedibus fxiscescentibus, digitis albicantibus ; mystaci- 

 busfiisco-nigris: vellere brevi, molli; cajnte parvulo, brevi. 



line. lin. 

 Longitudo ab apice rostxi ad caudse basin 3 2 



caudts 2 9 



ab apice rostri ad marginem oculi . 3^ 



ab apice rostri ad basin auris .... 7 



tarsi digitorumque 9 



auris 4f 



Hsec si^ecies muri musculo appropinquat ; difFert attamen capite 

 minore, (ratione ad magnitudinem habita,) rostro breviore, tarsisque 

 longioribus. 



Hub. Maldonado. 



Mus Maurus. M. pilis s^dirigidis, supra purpurascenti-nigris, 

 suhtks fnsco-plumbeis ; capite fuseo-nigro, rostro fuseo; auiibus 

 parvulis sordide albis, pilis minutissimis pallidii fuscis obsitis : 

 catidd corpus fere aquante, nigrd, pilis sparse vestitd: pedibus 

 fuscis ; mysta.cibus fusco-nigris, ad apicem grisescentibus. 



line. lin. 

 Longitudo ab apice I'ostri ad caudse basin ..11 3 



• caudcB 7 6 



• ab apice rostri ad marginem oculi . 1 



ab apice rostri ad basin auris .... 2 2 



tarsi digitorumque 1 8 



auris '. 61 



Ha:c species colore muri ratto appropinquat, at purpurascenti- 



f usco tincta. Quoad staturam murem decumanum pergrandem sequat ; 

 Vellus quoad texturam fer^ est ut in mure decumano ; et ad basin 

 plumbeum ; pilis albis in dorso lateribusque intersparsis. 

 Hal). Maldonado. 



" Though in the foregoing description I have retained the ge- 

 neric title Mus, I have here to state that the above species natu- 

 rally divide themselves into several subordinate groups, the characters 

 of which are sufficiently evident, not only between themselves, but 

 also between each group and that to which the term Mus ought, I 

 conceive, to be restricted, and of which our common mouse {Mus 

 musculus) may be regarded as the type. To these groups I shall here 

 assign subgeneric titles, and at the same time point out their chief 

 distinguishing characters without entering into any minute details 

 respecting them, as I shall shortly have an opportunity of illustrating 

 my views by means of drawings both of the teeth and of the animals, 

 without which it is impossible to convey a clear idea of the subject." 



Subgenus 1. Scapteromys*. 

 Molars with enamel deeply indented in the crown. In the front 

 molar of the lower jaw the enamel is indented twice on the outer 



* Scapteromys, from 'S,Ka.xTr,(>, a digger, and Mt/;. 



/ 



