462 REPORT OF NATIONAL MUSEUM, 1892. 



with tour or rive hens and the latter all lay their eggs in the same nest 

 until some thirty are deposited. The male bird incubates during the 

 night and the hens take turns during the day. 



The main facts to bear in mind here are that the eggs average about 

 30 in number, are ellipsoidal in form, and are unspotted, being a yel- 

 lowish-white in color, with a hard shell. The South American Ostriches 

 (Rhea ) essentially agree in these character's.* We meet with exceptions, 

 however, among the Ratitce in the Cassowaries and Emus. The mode 

 of incubation here is much the same as in the Ostriches, but Cassowa- 

 ries (Casuaridw) lay dark-green and rough-shelled eggs, while the 

 Emus (Dromceidm) make a shallow nest in the ground, in which they 

 lay from 9 to 13 eggs of a bluish-green to a dark bottle-green color; 

 the period of incubation being eighty days, the cock bird performing 

 the duty of hatching. Apieryx lays but a single egg two or three times 

 a year. It is enormous for the size of the bird, and is deposited in a 

 hole in the ground. Authors differ in their opinion as to the question 

 of incubation. Some hold it is performed by both sexes, while others 

 contend that it is performed only by the female. The Ratite birds are, 

 structurally, the most reptilian forms of the class Arcs we have in ex- 

 istence, yet were we to depend upon a study of their methods of incu- 

 bation and their eggs it would be but an uncertain clew as to what we 

 might be led to expect either in the higher groups of carinate birds, or 

 in existing reptiles, or in extinct forms of either class, or finally, in 

 lowly organized birds of other groups. We have the main facts, how- 

 ever, that in the Ratitce the eggs may in number range from one to 

 many; in color from yellowish- white to a green (never spotted or 

 streaked, etc.); in form ellipsoidal (always?); and incubated by one or 

 both of the sexes. Let us look at one or two other peculiar groups of 

 birds and then pursue the subject in a different direction. In the case 

 of the Penguins (Impennes), they lay two white or greenish-white eggs 

 in a rude nest on the ground or in a burrow, while, on theother hand, 

 the Tinamous (Grypturi) lay eggs which are "remarkable objects, curi- 

 ously unlike those of other birds. Their shell looks as if it were of 

 highly burnished metal or glazed porcelain, presenting also various 

 colors, which seem to be constant in the particular species, from pale 

 primrose to sage green or light indigo, or from chocolate brown to pink- 

 ish orange."t 



Incubation is performed by the male,! a strong Ratite character; nest 

 "a mere scrape, insufficiently lined with a few grass-leaves." § Herr 

 von Nathusius has further observed that the minute structure of the 

 eggshell of a Tinamou "is quite different from that of the true Galli, 



*Newton, A.: Art. "Rhea,'' Encyclo. Brit., 9th ed.. Vol. xx, p. 506. 

 t Newton, A. : Art. '•Tinamou," Encycl. Brit., 9th ed., Vol. xx.ni, p. 403. 

 t Bartlett, Mr. : P. Z. S.. 1868, p. 11."., PI. \n. 

 § Hudson, Mr.: In Argent. Orn. v. n, p. 210, 



