24 LIFE HISTORIES OF NORTH AMERICAN BIRDS. 



now and then one of their eggs has been found in the nests of other species, 

 such as the Wood-thrush, Robin, Catbird, Cedar-bird, Black-throated Sparrow, 

 Cardinal, and Mourning Dove. Such instances appear to be much rarer, how- 

 ever, than those in which they interlay with each other, and the majority of these 

 may well be due to accident, their own nest having possibly been capsized, and 

 necessity compelled the bird to deposit its egg elsewhere. Such instances do 

 occur at times with species that can not possibly be charged with parasitic 

 tendencies. 



There is a set of four eggs of the Meadow Lark (Ralph collection) before 

 me now, taken on May 6, 1892, in Volusia County, Florida, which in addition 

 contained an egg of the Florida Quail; another set of four eggs of the Gray- 

 tailed Cardinal, taken by Mr. H. P. Attwater, near Rockport, Texas, on April 28, 

 1893, and presented to the collection here, contains also an egg of the Scissor- 

 tailed Flycatcher, and I might cite other instances if I deemed it necessary. 



It is indisputable, however, that some latent traces of parasitism exist in our 

 Cuckoos, but these are not very frequent and seem to be principally confined 

 among themselves, and are apparently more prevalent among the Black-billed 

 species than the present one. Mr. Robert Ridgway tells me that he found 

 both species nesting in an apple orchard, near Mount Carmel, Illinois, in June, 

 1864, in adjoining trees, the two nests being not over 10 feet apart. 



Incubation, I think, lasts about fourteen days, and I believe the female 

 performs the greater portion of this duty. The young when first hatched are 

 repulsive, black, and greasy-looking' creatures, nearly naked, and the sprouting 

 quills only add to their general ugliness. If the eggs are handled the bird 

 frequently forsakes the nest, either throwing them out or abandoning them. 

 The eggs are elliptical oval in shape, about equally obtuse at either end ; the 

 shell is close grained, rather thin, and without gloss. The ground color varies 

 from a uniform Nile blue to pale greenish blue when fresh, fading out in time to 

 a pale greenish yellow. They are unspotted, but occasionally one or two eggs 

 in a set present a sort of mottled appearance, the ground varying somewhat on 

 different parts of the shell. Their color is one of those subtle tints which it is 

 difficult to describe. accurately. Many of the eggs resemble in tint some of the 

 lighter-colored Heron's eggs. 



The average measurement of sixty-six specimens in the United States 

 National Museum collection is 30.28 by 22.94 millimetres, or about 1.19 by 0.90 

 inches. The largest egg in the series measures 33.53 by 25.40 millimetres, or 

 1.32 by 1.00 inches; the smallest, 27.94 by 21.34 millimetres, or 1.10 by 0.84 

 inches. 



The type specimen, No. 25977 (PL 5, Fig. 1), from a set of three eggs, 

 was taken by Mr. D. B. Burrows, near Lacon, Marshall County, Illinois, on July 

 5, 1893, and presents the mottled appearance previously referred to. 



