covered by a tendinous membrane and skin. In the common
mole the eye is extraordinarily small but perfect, though
many anatomists doubt whether it is connected with the true
optic nerve; its vision must certainly be imperfect, though
probably useful to the animal when it leaves its burrow. In
the tucutuco, which I believe never comes to the surface of
the ground, the eye is rather larger, but often rendered blind
and useless, though without apparently causing any inconvenience
to the animal; no doubt Lamarck would have said
that the tucutuco is now passing into the state of the
Asphalax and Proteus.

Birds of many kinds are extremely abundant on the undulating,
grassy plains around Maldonado. There are several
species of a family allied in structure and manners to our
Starling: one of these (Molothrus niger) is remarkable from
its habits. Several may often be seen standing together on
the back of a cow or horse; and while perched on a hedge,
pluming themselves in the sun, they sometimes attempt to
sing, or rather to hiss; the noise being very peculiar,
resembling that of bubbles of air passing rapidly from a small
orifice under water, so as to produce an acute sound. According
to Azara, this bird, like the cuckoo, deposits its eggs
in other birds' nests. I was several times told by the country
people that there certainly is some bird having this
habit; and my assistant in collecting, who is a very accurate
person, found a nest of the sparrow of this country (Zonotrichia
matutina), with one egg in it larger than the others,
and of a different colour and shape. In North America
there is another species of Molothrus (M. pecoris), which