84 



THE OOLOGIST 



Eggs of Birds and Reptiles. 

 By R. W. Shufeldt, Washington, D. C. 

 As every one now knows who has 

 paid any attention to tlie subject, mod- 

 ern reptiles and modern birds have 

 arisen — or descended, as yuu clioose — 

 from a common stock that was in ex- 

 istence far, far back in geologic time. 

 The truth of this is as well established 

 as anything biology has to offer, and 

 far better established than some other 

 accounts we read, referring to the ori- 

 gin of living forms on this planet and 

 their relationships. 



In the structure of many existing 

 species of birds, we meet with vesti- 

 geal evidences pointing to their rep- 

 tilian ancestry, and these were, in 

 some extinct species, far more pro- 

 nounced, as is well shown in the fossil 

 remains we have found of them. For 

 instance, some of the great, extinct 

 divers of the Cretaceous Beds of Kan- 

 sas possess teeth, these being struc- 

 tures which no bird now living ex- 

 hibits the barest vestige of along the 

 opposed margins of its jaws. 



Most intelligent observers and gen- 

 eral readers, however, are, in these 

 days, more or less familiar with all 

 such matters, even the scholars of the 

 high-schools having found them in 

 their text-books. So, then, I will not 

 touch upon them in the present arti- 

 cle, but reserve my space for the pre- 

 sentation of other points, by means of 

 which we may still further contrast 

 reptiles and birds. 



For example, it is to be noted 

 that a very large proportion of the 

 species of birds now representing the 

 existing world's avifauna build very 

 elaborate nests in which to lay their 

 eggs and rear their young. Some birds, 

 however, build no nests at all, but lay 

 their eggs on the bare ground, rock, 

 or elsewhere, and their young are 

 hatched out in such places. Others 

 lay their eggs in burrows which they 



excavate for themselves, as the wood- 

 peckers do in the trunks or trees, or 

 as kingfishers, and martins, and many 

 other species do, by digging subter- 

 ranean tunnels for themselves. Again, 

 some birds are parasitic by nature and 

 deposit their eggs in the nests of 

 other species, abandoning their young 

 to the tender mercies of the foster 

 parents, as do cuckoos, cowbirds and 

 others. Then there are the mound 

 birds or megapodes of Australia, Sa- 

 moa and elsewhere, which bury their 

 eggs in immense mounds of earth and 

 vegetable matter erected by them- 

 selves, and there leave them to hatch 

 out. Their young fly almost at once, 

 having very promptly assumed the 

 plumage of the adults ; indeed, we may 

 say the indentification and deposition 

 of the eggs on the part of birds not 

 only varies greatly in different groups, 

 but is extremely interesting. In this 

 connection it may be said that no 

 species of bird now in existence is 

 viviparous — that is, brings forth its 

 young alive; nor are any ovo-vivipar- 

 ous, or where the eggs are retained in 

 the oviduct until complete develop- 

 ment of the embryo takes place. 



Many birds lay pure white eggs, 

 while in the case of others a few 

 specks may be distributed over the 

 surface, or else confined chiefly to the 

 butt or larger end. From these im- 

 maculate ones and the sparsely speck- 

 led varieties, the eggs of birds pre- 

 sent an almost endless series in the 

 matter of form, coloring and mark- 

 ings. The beauty of some is extraor- 

 dinary and almost transends our pow- 

 ers of description. 



None of the Reptiles — snakes, liz- 

 ards or turtles — in so far as I am 

 aware, build any structure which may 

 be dignified by the name of "nest." 

 Most Chelonians, or turtles, bury the 

 eggs beneath the surface of the 

 ground, and marine turtles beneath 



