Vol. XVI. 



.916 



] SnuFELDT, Fossil Birds' Eggs. 85 



usually be demonstrated by the careful use of a high-power, com- 

 pound microscope, seconded l)y an exhaustive chemical analysis 

 of the shell and its contents. Further on in the present article 

 this matter will be touched upon again, when the examination of 

 some actual specimens is taken up. 



There are not a few geologists and palaeontologists who contend 

 that all the " so-called fossil eggs of birds and reptiles " are 

 nothing more nor less than " concretions." These formations are 

 now well known, and have been frequently described in text-books 

 on geology, rendering it quite unnecessary to discuss them here.* 

 These nodular concretions are often found where they have 

 assumed the perfect ovate form of an egg, as the egg of a domestic 

 fowl {Gallus), for example. Where such concretionary formation 

 subsequently comes to be, in some way, overlaid with a thin 

 coating of calcareous deposit, and by some action or other this 

 wears down to a more or less smooth surface, the entire specimen, 

 when finally discovered by man, most assuredly has all the 

 characters of what we would imagine the fossil egg of a bird 

 possessed. Such ovate, thin, finely-granulated, lime-coated, 

 nodular concretions have been mistaken by many observers ancl 

 discovei^ers of them for what they certainly are not — fossilized 

 birds' eggs. Wherein they differ from the latter I shall proceed 

 to demonstrate. 



First, however, as to the source of the material at hand. This, 

 as a whole, has been turned over to me for description by Mr. 

 Charles W. Gilmore, Curator of the Department of Fossil Birds 

 and Reptiles, of the U.S. National Museum, to which institution 

 the specimens belong. Mr. Gilmore was especially kind in 

 placing at my disposal all the information he had in his possession 

 with respect to these alleged examples of fossil birds' eggs, as 

 well as all there were of them in the collection. They may be 

 listed as follows : — 



List of Specimens. 



I. — " Fossil Egg." Cat. No. 8,262, Quinn Draw, Washington Co., 



South Dakota. Oligocene. (Upper Titanotherium Beds.) 



1888. Collected and presentecl by J. W. Gidley (see Plate L, 



figs. 1-3)- 

 2. — " Fossil Egg." Cat. No. 4,891, Galistes, Santa Fe Co., New 



Mexico. Received from F. H. Wiley, Nov., 1900. 



(Horizon not known.) (See Plate I., fig. 4, and Plate V., 



fig- 16.) 

 3. — " Fossil Egg." Cat. No. 6,496. St. Gerand de Puy, France. 



Oligocene. Gift of Dr. R. W. Shufeldt, 1896. (See Plate 



v., fig. 12.) 

 4. — " Fossil Egg." Cat. No. 6,498. St. Gerand de Puy, France. 



Oligocene. Gift of Dr. R. W. Shufeldt, 1896. (See Plate 



v., figs. 14 and 15.) 



* Le Conte, Joseph, "Elements of Geology," New York, 1883 (rev. ecL), 

 pp. 188-190, fig. 173. 



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