50 MALDONADO. tciiAi'. ni. 



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 representative 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 

 citckoos are the only birds which can be called truly parasitical : 

 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 cause theirs during the 

 period of infancy." It is remarkable that some of the species, but 

 not all, both of the Cuckoo and Molothrus should agree in this one 

 strange habit of their parasitical propagation, whilst opposed to each 

 other in almost every other habit : the molothrus, like our starling, 

 is eminently sociable, and lives on the open plains without art or 

 disguise : the cuckoo, as every one knows, is a singularly shy bird; 

 it frequents the most retired thickets, and feeds on fruit and cater- 

 pillars. In structure also these two genera are widely removed 

 from each other. Many theories, even phrenological theories, have 

 been advanced to explain the origin of the cuckoo laying its eggs 

 in other birds' nests. M. Prevost alone, I think, has thrown light 

 by his observations f on this puzzle : he finds that the female 

 cuckoo, which, according to most observers, lays at least from four 

 to six eggs, must pair with the male each time after laying only 

 one or two eggs. Now, if the cuckoo was obliged to sit on her own 

 eggs, she would either have to sit on all together, and therefore 

 leave those first laid so long, that they probably would become 

 addled ; or she would have to hatch separately each egg or two 

 eggs, as soon as laid : but as the cuckoo stays a shorter time in 

 this country than any other migratory bird, she certainly would 

 not have time enough for the successive hatchings. Hence we can 

 perceive in the fact of the cuckoo pairing several times, and laying 



* Magazine of Zoology ami Botany, vol. i. p. 217. 



t Kead before the Academy of Sciences in Puris. L'luslitut, 1834, p. 418. 



