88 Shufeldt, Fossil Birds' Eggs [^^^' 



2nd Oct. 



later, through tilting, their planes formed, over various areas, an 

 inclined watershed, and erosion set in. During the enormous 

 lapses of time following upon this, the rains carved out the 

 immense hills and divides of that region as we now find them. 

 No vegetation to speak of appeared ; and, as the sculpturing went 

 on, fossils, among other things, were exposed. The rains fre- 

 quently carved aroimd these, as I stated above, leaving them 

 surmounting cones of the hard clay in numerous places. This 

 fossil egg, as pointed out above, occupied the apex of such a cone 

 at the time of its discovery. Mr. Gidley was descending into one 

 of these divides, following a companion. In the course of his 

 descent he slipped ; and, throwing back his hand to steady him- 

 self, he seized the peak of one of these small cones, the apex of 

 which, breaking off in his hand, proving to be, much to his delight, 

 the fossil bird's egg here being described. 



It is said that Prof. E. D. Cope, on one of his expeditions into 

 these terres mauvais, once discovered the fossil skull of some large 

 animal surmounting one of these conical peaks. The latter was 

 so high that it had to be pulled over by means of a rope before he 

 could obtain the coveted specimen. 



By the aid of a powerful microscope I have, with great care, 

 examined all the microscopical slides of the cross and surface 

 sections of the shell of the fossil bird's egg shown in figs. 1-3 of 

 Plate I., as well as the corresponding ones of the shell of an egg of 

 Crex globicera made by Gidley and Tassin, and I find that the 

 intimate, minute structure of these egg-shells differs but very 

 slightly for the fossil and the existing bird. Indeed, such an 

 examination leaves no doubt in the mind of the microscopist but 

 that the fossil specimen is the fractured shell of an egg of some 

 bird of the period mentioned — Oligocene. There is a chance, of 

 course, of its having been the egg of some reptile, and not a bird 

 at all ; though I think the ovate form of the egg indicates avian 

 rather than reptilian parentage. 



It is quite impossible to say whether the bird that laid that 

 egg is still represented as a species in the existing avifauna or not, 

 although the chances are that it is an extinct form. 



There will be no necessity for my going any further into the 

 results of the microscopic examination of the shells of eggs of 

 extinct and existing birds, in so far as a consideration of the 

 material before me is concerned. From all that has been set 

 forth, from the study of the figures in the plates, and from what 

 is given about them under " Explanation of Plates," the 

 similarity of the two structures or their histological resemblance 

 will have been amply demonstrated. 



Finally, as there is no saying what kind of bird laid this egg, 

 it will be of no advantage to science to bestow a name upon it. 

 Moreover, we now know that not a few of the birds of the Oligocene 

 belonged to genera still in existence, and in no way differed from 

 their present-day descendants beyond their specific differences. 

 Among the former we have, up to date, such birds as Grebes, Gulls, 



