226 Shufeldt, Eggs of Reptiles and Birds Compared. [i^t^ApHi 



of the class as a whole, are thus being destroyed. For instance, 

 the Moas are all gone, the Apteryx will soon follow, while similar 

 examples are to be found in many other parts of the world. 



It is very certain that, for several million years past, birds of 

 one species or another have laid eggs similar in all respects to those 

 laid by certain species of existing avifauna in various regions of 

 the earth ; they have had the same forms — ellipsoidal, broadly 

 ellipsoidal, spherical, ovate, broadly ovate, and so on. Recently, 

 I have presented a paper on " Fossil Birds' Eggs," in which all 

 this is touched upon ; and in fig. i, Plate XXXVII. . will be seen 

 an ellipsoidal egg of a bird that thrived during the Oligocene 

 of France, it being a specimen at this time in the collection of 

 the U.S. National Museum. There were also birds during the 

 Oligocene period, that laid eggs of an ovate form, just as many 

 species do to-day ; but whether these eggs were all white, or 

 exhibited markings of any kind, we have, at this time, no means 

 of knowing. Their contents were doubtless the same, and the 

 shell structure was certainly the same — a fact proved in my forth- 

 coming paper on fossil birds' eggs by the figures of microscopical 

 sections, the latter compared with similar sections of an egg-shell 

 of an existing bird. 



Whether any birds — ancient or modern — ever laid eggs wherein 

 the shells were more or less soft and flexible, such as those 

 deposited by certain existing marine turtles, I am, at this time, 

 unable to say. By birds is meant here such vertebrates as, at 

 any time, possessed true feathers, irrespective as to whether the 

 forms having them could fly or not. Some reptiles lay but a few 

 eggs each season, while others deposit a large number at one time, 

 as, for example, the marine turtle Caretta imhricata, which has 

 been known to lay as many as two hundred and fifty to a clutch. 

 It is impossible now to ascertain data on this point with respect 

 to birds of former ages, as, for instance, those birds that existed 

 during the Ohgocene or the Jurassic periods of geologic time. 

 Modern birds vary remarkably in this particular, some species 

 laying but a single egg to the " set," while others may lay as many 

 as a score or more. It is an interesting fact that in some species 

 the females all deposit their eggs in the same nest, which is the 

 case with the Ostrich.* 



Birds, as is well known, deposit their eggs in a great variety of 

 places, as in all manner of nests of their own construction ; in the 

 nests of other birds ; in burrows ; in mounds ; on the bare ground, 

 sand, or rocks ; in hollows of tree-trunks, made by themselves, 

 or those already a part of the tree, and so on through other habits. 

 In these respects avian nidification has. in time, in many instances, 

 passed through a truly wonderful evolution : but we are familiar 

 with it only in so far as it is manifested in the existing forms of 

 birds, or, rather, those of the world's existing avifauna wherein 

 such habits thus far have come to be known to science. 



* Newton, Alfred, " A Dictionary of Birds," p. 664. 



