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 o^gg 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, ^ 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 aitd Botany, vol. i. p. 2 1 7. 



