COMPARATIVE OOLOGY OF NORTH AMERICAN BIRDS. 465 



Megapodes lay bricJc-red eggs, and Sharpe tersely remarks in his Classi- 

 fication of Birds, "Nest none. Eggs deposited in a mound raised by 

 many of the birds in concert. Young hatched without the intervention 

 of the parent bird, and able to fly almost from birth" (p, 68). It would 

 seem then that in the nesting habits of the Megapodes, we see not a little 

 to remind us of the corresponding habits in some oft he reptiles. Ac- 

 cording to Gibson crocodiles -'are oviparous, depositing their eggs, 

 from 20 to GO in number and inclosed in a calcareous shell, in holes 

 made in the sand or mud of the river side, where they are left to be 

 hatched by the heat of the sun, or as in the case with certain Ameri- 

 can species, in hillocks formed by themselves which they hollow out 

 and fill with leaves and other decaying vegetable matter, where the 

 eggs are hatched by the heat generated in the decomposing mass."* 

 The very distinguished herpetologist, Prof. E. D. Cope, also briefly 

 writes me thus, his communication being dated Philadelphia, Decem- 

 ber 15, 1892 : "As to reptile eggs I know of noneexcepting those of Croc- 

 odilia, which are not elliptic and white. Tortoises lay more eggs than 

 either lizards or snakes, so far as known. No incubation among rep- 

 tiles is known to me excepting in the cases of Pythonid snakes. I 

 must add that a great deal remains to be known on the subject/' 



Among the Craces the nest is placed in a tree, the eggs are white 

 and two in number. (Sharpe, loc. cit., p. 68.) 



With the facts that I have enumerated in the foregoing paragraphs 

 at our command, we can next pass to the consideration of tiie oology 

 of the various groups of birds occurring in the avifauna of the United 

 States, and here, relying as 1 do upon the published works of authors, 

 who are widely recognized as authorities in such matters, I find the 

 greatest amount of variance in the descriptions. These differences of 

 opinion refer to the number of eggs laid by any particular species of 

 bird, to the coloration of the eggs, and to the questions of nesting and 

 incubation. In cases where, from the rarity of specimens, or where 

 the eggs of certain species are known to vary even in the clutch laid 

 by the same individual, and so on, there may be some excuse for this 

 but in cases where hundreds or even thousands of eggs of the same 

 species have been examined by competent describers, it would seem 

 that it is about time we had something like uniformity in description. 

 This is only too frequently not the case, as the reader later on will soon 

 discover. 



Among our more lowly organized groups of birds stand the Divers 

 (Uriiiatoroidea), and Grebes (Podicijioidca). related as they are to the 



leading to and from the bole by making many other tracks and scratches in the 



neighborhood. It lays eggs only at night. * All these birds seem to be semi- 



nocturnal. The eggs arc all of a rusty-red color, and very large for the 



size of the bird." 



* Gibson, John, Art. "Crocodile." Encycl. Brit., 9th ed., vol. vi, p. 593. 

 H. Mis. Ill, pt. 2 30 



