32 ON THE MAMMALS OF THE ARGENTINE REPUBLIC. (Jan. 16, 
15. SoMATERIA SPECTABILIS. 
The only Eider noticed north of Cape Union ; breeding in limited 
tuumbers. 
16. BERNICLA BRENTA. 
Not uncommon along the shores of the Polar Basin, breeding. 
2. Notes on some of the smaller Mammals of the Argentine 
Republic. By Henry Durnrorp. 
[Received December 18, 1876.] 
[Mr. Henry Durnford, now resident near Buenos Ayres and 
well known as a diligent collector of birds, has sent me specimens of 
three small Mammals, with the subjoined notes on their habits. I 
trust he may be induced to continue his researches in this depart- 
ment, as the smaller Rodents of La Plata are still very imperfectly 
understood. Mr. Alston has kindly determined the species.—P. L. 8. ] 
1. Hesperomys vuxtpinus (Licht.); Burm. Syst. Ueb. Th. 
Bras. i. p. 163. 
This Rat is not common, and from its habits and the inaccessible 
places it frequents is difficult to obtain. Hitherto I have only found 
‘it in lagunes to the north of Buenos Ayres, where the reeds and 
aquatic plants afford plenty of cover. In these extensive swamps it 
lives, making a large oval nest of rushes and grass, the finer fibres 
towards the interior, and generally building its dwelling about a 
foot above the water, amongst the reeds, but sometimes higher than 
this. It swims and dives with great ease and rapidity. Its food, 
so far as I have observed from the only two specimens I have 
obtained, consists of aquatic weeds and grass. 
2. HespERomys ELIuRUS, Wagner; Burm. op. cit. p. 173. 
This Mouse is found in the same places as the preceding species, 
and is much more common than that animal. It lives amongst 
thick reeds, making a small oval nest of grass and fine rushes. Its 
chief peculiarity is the length of its hind legs, which enables it to 
take enormous leaps for so small an animal ; and this is very neces- 
sary, as its only means of escape is by jumping from its nest, some- 
times three feet above the water, into the weeds which cover the 
surface of the lagunes. It dives and swims with great rapidity. It 
is very often found in the nests of Synallaxis melanops, which are 
numerous, and yenerally about the same height above the water as 
its own. 
3. DipeLpHys crassicaupAta (Desm.). 
This is the Comadreja colorada of the country. It is rare, lives 
in old hollow trees, roofs of houses, &c., and sometimes commits 
great havoc in the poultry-yard. The other species of Comadreja' 
is quite common. 
1 [Didelphys azare?—Ep. | 
