54 
MALDONADO 
CHAP. 
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 Aspalax and 
Proteus. 
Birds of many kinds are extremely abundant on the un¬ 
dulating grassy plains around Maldonado. There are several 
species of a family allied in structure and manners to our Star¬ 
ling : 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, plum¬ 
ing 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 cer¬ 
tainly 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 has a similar cuckoo-like habit, and which is 
most closely allied in every respect to the species from the 
Plata, even in such trifling peculiarities as standing on the 
backs of cattle ; it differs only in being a little smaller, and in 
its plumage and eggs being of a slightly different shade of 
colour. This close agreement in structure and habits, in repre¬ 
sentative species coming from opposite quarters of a great 
continent, always strikes one as interesting, though of common 
occurrence. 
Mr. Swainson has well remarked, 1 that with the exception 
of the Molothrus pecoris, to which must be added the M. niger, 
the cuckoos are the only birds which can be called truly para¬ 
sitical ; namely, such as “ fasten themselves, as it were, on 
another living animal, whose animal heat brings their young 
into life, whose food they live upon, and whose death would 
1 Magazine of Zoology and Botany, vol. i. p. 217. 
