from Xorth-western Patagonia. 209 



brain-case, and rounded iiiterorbital region. \n Notiomys^on 

 the other hand, tho skull is short and bread, with short 

 conical inuz/h*, very Itrojid and squarc-edj^cd interorl)ital 

 region, and .strongly built brain-c;ise. Both have equally 

 the remarkably small molars, by which they may be distin- 

 guished from any other known romis. 



Nearly related to Allen's Oxymycteriis microtis are two 

 earlier-<li'scribed species — //esperoniys (Arodon) Diichaeheui^ 

 l\Iatschie, and Oxi/myct( rus raldirianit't, Philippi — and n)y 

 present material ineludos specimens referable to the latter, as 

 well as the l'J03 example of microtis. 



But I cannot agree that these forms shoidd be put actually 

 iniu (Krynii/ctenis, and nc)W propose to make of them a new 

 genus, which may be described as follows : — 



Geoxus, gen. nov. 



Allied to Od'i/mf/derus, but form more highly modified for 

 burrowing, with velvety fur and very siiort tail. 



Skull with no trace of squared edges to the iiiterorbital 

 space. Zygomatic plate narrow, more vertical than in 

 LKryiuy citrus^ its front edge scarcely proJL-ctiMg. 



Incisors more slender and molars proportionally very much 

 smaller than in the allied genus. Tho latter character also 

 present in Xotiomys. 



Genotype. uVoto.cus fossor, sp. n. (This selection is made 

 to avoid any complications due to wrong identificalion of the 

 otiier ft)rms known — though I have really no doubt about 

 any of them.) 



Other species : lyiichaelaeni, Matsch., valdivianus^ Phil., and 

 microtis^ All. 



The excellent description and figures given by Dr. Allen 

 of ^V. microtis will readily show the characters of this new 

 genus. Matschie has also given figures of iV. michaeheni. 



With regard to the species i\'. /oa'ao/-, it may be defined as 

 follows : — 



Essential characters as in N. microtis, but the fur even 

 more thick and velvety and the general colour dark smoky 

 gieyish (" deep mouse-grey "), with none or scarcely any of 

 tlie yellowish or drabby ticking which is described by Allen 

 and is niaikedly present in our Kosknvsky sj)eciinen of 

 microtis. Under surface rather lighter groy, with a slight 

 drabby suffusion ; the liaiis all broadly slaty at base, grey 

 terminally, those on the chin alone greyish white to their 

 bases. 



fcjkull, as ill ^V. 7)iicrotis^ with the palatal foramina only 



