132 - BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
von Richthofen,' the superficial deposits of these basins were laid down 
over the bottoms of isolated salt lakes having no outlet, and were after- 
wards partially buried by alluvial detritus. The moderate depth to 
which ravines have cut through the ancient lake beds, and the straight 
narrow gorge of the Sang Kan, through which the waters were drained off, 
corroborate the belief that this event took place at no very remote period. 
At all hazards, it is certain that no earlier age can be assigned to the 
gravel beds from which the fossil egg was exhumed than the Pleistocene. 
Turning our attention now to the specimen itself, we notice that it 
presents almost exactly the same appearance as the Russian egg de- 
scribed by Brandt, a comparison with which has been facilitated by | 
means of a plaster cast very kindly presented to the Museum by this 
author. In size, symmetry of contour, and all outward respects, the 
two are remarkably alike. ‘The only noticeable difference is im respect 
to weight, but this is readily explained by the mineral infiltration already 
referred to in the case of the type, and the absence of such replacement 
in the present example. Assuming that none of the internal calcareous 
mass has been lost, the Chinese egg must have weighed originally about 
337 grams, as against “nicht ganz zwei russische Pfunde” for Brandt’s 
specimen. The weight of our individual, as given in the subjoined table, 
is for the empty shell, perforated at one end in the manner already de- 
scribed. The mutilation cannot be said to be altogether regrettable, 
however, since it permits of an inspection of the interior, and facilitates 
a measurement of the volume (equal to the loss of weight in water), 
cubic contents, and specific gravity of the object. 
Measurements of a number of other eggs were made in like manner, 
and the results are tabulated herewith for the sake of comparison. In 
the case of the South American ostrich, an average-sized and also a 
large-sized individual were selected from a collection of over two dozen 
contained in the Museum of Comparative Zodlogy. The dimensions of 
Epyornis and Dinornis eggs are taken from the literature of these 
genera, excepting No. 3 of the list, which were derived from a plaster 
cast obtained from the Paris Museum of Natural History. For these 
two genera the cubic contents have been calculated from the formula of 
an ellipsoid of revolution (since no data are at hand to show that they 
have ever been ascertained by direct experiment) and, not being cor- 
rected for the thickness of the shell nor for its departure from the figure 
1 Loc. cit., p. 344 et seg. Also Vol. I. p. 110, quoted in Whitney’s ‘ Climatic 
Changes” as follows: “It may be stated as a certainly ascertained fact, that 
in Central Asia a dry climate has prevailed for a long time.” 
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