456 MR. O. THOMAS ON A COLLECTION OF [Julie 17, 



the pads large and prominent. Thumb with a large and prominent 

 nail, but not a claw. Other fingers with very long claws, 4 to 

 5 millim. in length. Eifth hind toe, without claw, reaching to the 

 middle of the first phalanx of the fourth. Mammae 8, two pectoral 

 and two inguinal pairs. 



Skull rather narrow ; upper margin of the orbit rounded, quite 

 without ridges ; interparietal remarkably small, only 4 millim. in 

 breadth and 1^- in an antero-posterior direction. Incisive foramina 

 reaching to the first fold of the anterior molars. Incisors pale 

 yellow above, nearly white below. Muzzle rather long and low, 

 only 4'2 millim. in height at the anterior end of the palatine 

 foramina. Lower jaw very thin and slender, only 7 millim. from 

 the top of the coronoid to the tip of the angular process. Coronoid 

 higher than condyles. 



This species seems to be a house-haunting one, as the two 

 Maraynioc specimens are labelled by M. Jelski as domestic Mice. 



Gay's specimen had a tail only 50 millim. in length, but his de- 

 scription of the coloration is too exact to admit any doubt that the 

 present is really his species. 



. H. scalops, owing to its elongated claws, was placed in the sub- 

 genus Oxymycterus by its describer, but, just as in the case of II. 

 megalonyx, Waterh., the skull proves it to belong to Habrothrix, of 

 which it is by far the most brightly marked member. 



9. H. (Habrothrix) olivaceus, Waterh. S. No. 12. 

 a, b. Two specimens. Maraynioc. 



These two specimens, like those, quite similar, collected byM. Stolz- 

 mann, I refer to H. olivaceus ; but larger series from different localities 

 are needed before the exact relations between H. olivaceus, arenicola, 

 obscurus, caliginosus, and the other Vole-like Vesper-mice of the 

 Patagonian subregion can be properly made out. 



10. H. (Habrothrix) caliginosus, Tomes (?). S. No. 13. 

 a to m. Thirteen specimens. Junin and Amable-Maria. 



In 1882 I placed, with considerable doubt, some specimens under 

 Mr. Tomes's II. caliginosus, and in the same way I now refer these 

 specimens, which are quite identical with those of M. Stolzmann, 



