422 troxell: fossil birds' eggs 



the solution containing 5 grams of ammonium chloride per 200 

 cc. of solution (or an equivalent amount of hydrochloric acid) 

 add a few drops of methyl red (0.2 per cent alcoholic solution) 

 and heat the solution just to boiling. Carefully add dilute 

 ammonium hydroxide, dropwise, till the color of the solution 

 changes to a distinct yellow. Boil the solution for one or two 

 minutes; filter. Wash the precipitate thoroughly with hot 

 2 per cent ammonium chloride, or nitrate, solution. t Ignite in 

 a platinum crucible and, after the carbon is all burned off, blast 

 for five minutes; cover the crucible and place it in a desiccator 

 till cool. Weigh (covered) as rapidly as possible. A second 

 blasting of five minutes is desirable to facilitate rapid weigh- 

 ing, and thus to secure what are probably more accurate results. 



PALEONTOLOGY.— Oligocene fossil eggs. Edward L. Trox- 

 ell, Ann Arbor, Michigan. (Communicated by H. H. 

 Bartlett.) 



Fossil remains of birds are rare. It is of unusual interest 

 therefore to note the finding of two fossil eggs from the Oli- 

 gocene bad-lands near Harrison, Nebraska. The specimens, 

 which are elongated and slightly smaller at one end, resemble 

 both in size and shape those of the domesticated chicken or of 

 the Mallard duck. The very rugose outer surface, not found 

 •on the eggs of most modern birds, is, however, characteristic 

 of those of the gull, and it is entirely in harmony with the theory 

 of their deposition that they should have been laid by a water 

 fowl. The shell, which measures about 0.6 mm. in thickness, 

 still retains its calcium phosphate, the only part of the specimen 

 which we can say definitely is a remnant of the original. (This 

 chemical test is due to the courtesy of Mr. R. W. Clark of the 

 Mineralogy Department of the University of Michigan.) 



The first of the two specimens above mentioned was found 

 by Mr. Vernon Marsteller, of Wayne College, who was a member 

 of my party in 1915. Fossil eggs are mentioned in the South 

 Dakota Geological Survey Report, Bulletin 9, by C. C. O'Harra, 

 and one is fully described by 0. C. Farrington in Publication 

 35 of the Field Columbian Museum, 1899. 



