228 Shufeldt, Eggs nf Reptiles and Birds Compared. [j^fA^ii 



Ellipsoidal birds' eggs are far more frequently met with, and, 

 in addition to the one of a Megapode already alluded to (fig. 3), 

 I present on the other plates a series form the TrochUi (tigs. 4-9, 

 Plate XXXVIII.) ; one of a Cockatoo [Cacatna roseicapilla) (Plate 

 XXXVIII., fig. 18) ; and those of the common Night-Hawk of 

 the eastern section of the United States {Chordeiles virginianus) 

 (Plate XXXIX., figs. 23 and 24) ; also those of the Owlet-Nightjar 

 of Austraha [Mgotheles novcB-hollandice) (Plate XXXIX., figs. 25 

 and 26). 



I have also jihotographed the ellipsoidal eggs of the Guira guira, 

 of South Am.erica, a cuculine species that lays a most remarkable 

 egg of a pale blue, with a raised network of white covering the 

 external surface of the shell all over. Mr. Heilmann published 

 one of my ]:)hotographs of the Gtiira in the work cited in a former 

 paragraph. 



The ellipsoidal eggs of birds are not always plain white, then ; 

 for we meet with many exceptions to this, not only in the Guira 

 just mentioned — and a good example of this — but the two Night - 

 Hawks' eggs on Plate XXXIX. (figs. 23 and 24) are interesting speci- 

 mens illustrating the same point. However, did we but know of 

 all the ellipsoidal eggs that existing birds lay, I am of the opinion 

 that we would find the vast majority of them without any markings 

 whatever — that is, we would find them to be pure white, like the 

 egg of the turtle seen in fig. 22. 



Another interesting feature occasionally to be met with among 

 the eggs of birds is where the egg of one species will closely 

 resemble the egg of another form belonging to an entirely different 

 and distantly related group of birds. Mr. Court has several good 

 examples of this in his collection, and one of these I have selected 

 to illustrate this point. A very beautiful example is seen in 

 figs. 20 and 21 — the first being an egg of the Burrowing Owl and 

 the second an egg of the Belted Kingfisher. This comparison is 

 made the more remarkable when we come to compare two other 

 eggs of the Burrowing Owl — of the same clutch — which very 

 markedly differ not only in form but in size. These eggs are 

 shown on the same plate for comparison (figs. 27 and 28). In 

 fact, the comparison of the Kingfisher's and Owl's eggs on 

 Plate XXXIX. of this article, shown in figs. 19-21 and 27 and 28, 

 is an object lesson in oology to which attention is but rarely 

 invited in books. 



Passing from the questions of the form and size of eggs, as they 

 throw any hght on the affinities of birds and reptiles, or upon 

 other matters within the former group, it will be as well to add 

 a few words upon other characteristics of birds' eggs, which, as 

 a rule, stand among the most beautiful objects in all nature. One 

 of the most remarkable instances I have ever met with in the 

 coloration of birds' eggs is exemphfied in a set of three eggs of the 

 Least Tern {Sterna antillarum) in the collection of Mr. Court. 

 (Plates XL. and XLL, figs. 29-31, 39-41. Here 29 and 39 are 

 the same egg ; so, too, are 30 and 40, and 31 and 41. In photo- 



