from North-western Patagonia, 209 
brain-case, and rounded interorbital region. In Notiomys, on 
the other hand, the skull is short and broad, -with short 
conical muzzle, very broad and square- -edged interorbital 
region, and strongly built brain-case. Both have equally 
the remarkably small molars, by which they may be distin- 
guished from any other noun forms. 
Nearly related to Allen’s Oxymycterus microt’s are two 
earlier-described species—Hesperomys (Acodon) michaelseni, 
Matschie, and Oxymycterus valdivianus, Philippi—and my 
present material includes specimens referable to the latter, as 
well as the 1903 example of microtis. 
But I cannot agree that these forms should be put actually 
into Oxymycterus, and now propose to make of them a new 
genus, which may be described as follows :— 
GEOXUS, gen. nov. 
Allied to Oxymycterus, but form more highly modified for 
burrowing, with velvety fur and very short tail. 
Skull with no trace of squared edges to the interorbital 
space. Zygomatic plate narrow, more vertical than in 
Oxymycterus, its front edge scarcely projecting. 
Incisors more slender and molars proportionally very much 
smaller than in the allied genus. The latter character also 
present in Wotiomys. 
Genotype. Wotorus fossor, sp. n. (his selection is made 
to avoid any complications due to wrong identification of the 
other forms known—though I have really no doubt about 
any of them.) 
Other species : michaelseni, Matsch., valdivianus, Phil., and 
microtis, All. 
The excellent description and figures given by Dr. Allen 
of NV. microtis will readily show the characters of this new 
renus. Matschie has also given figures of NV. michaelseni. 
With regard to the species JV. fossor, it may be defined as 
follows :— 
Essential characters as in WN, microtis, but the fur even 
more thick and velvety and the general colour dark smoky 
greyish (‘‘ deep mouse-grey ’’), with none or scarcely any of 
the yellowish or drabby ticking which is described by Allen 
and is markedly present in our Koslowsky specimen of 
microtis. Under surface rather lighter grey, with a slight 
drabby suffusion ; the hairs all broadly slaty at base, grey 
terminally, those on the chin alone greyish white to their 
bases. 
Skull, as in NV, microtis, with the palatal foramina only 
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