128 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
The matrix from which the specimen was washed out is stated by 
Brandt to have been a reddish brown friable loam, overlying a bed of 
crystalline gypsum. So symmetrical was the shell in outline that it 
was wellnigh impossible to determine which end corresponded to the 
acute, and which to the obtuse pole of ordinary birds’ eggs.’ Being 
perfectly intact, little more could be done than to note its general ex- 
ternal appearance, and ascertain its weight and dimensions. The weight, 
which fell a trifle short of two Russian pounds, was found to be dispro- 
portionate to the thickness, but is probably to be accounted for by the 
mineral infiltration observed by Nathusius. According to the latter, 
portions of the interior were lined with a crystalline deposit having a 
thickness of 1.8 cm. in places, and there was also a quantity of loose cal- 
careous matter within the ovulite, supposed to represent the fossilized 
membrana teste. 
The capacity of the egg, that is to say, its cubic contents, was deter- 
mined by Brandt indirectly from the displacement of a plaster cast 
in water, which amounted to upwards of 2200 c.cm. Allowing say 
125 c.cm. for the volume of the shell substance itself, the actual capacity 
of the interior is seen to be about 2075 c.cm., as indicated in the table 
on page 133. Now, as the shell of the largest known ostrich egg has 
only two thirds this capacity, it is plain that the fossil egg must be the 
legacy of a larger bird than the ostrich, and very likely one differing in 
other respects as well as size. That the egg belonged to some Struthions 
bird is shown in a convincing manner by the microscopic structure, 
which is eminently characteristic of the group.” But in the absence of 
direct skeletal evidence, such as might have been afforded by associated 
bones, it seems inadmissible to refer so huge an egg to the same genus 
as the living ostrich. Therefore we are inclined to dissent from the 
proposition of Nathusius to abandon the genus Struthiolithus, which 
was very properly created for its reception by Brandt, and agree with 
1 On the cause and significance of polar deformation of egg shells, compare the 
following suggestive papers: Ryder, J. A., The Mechanical Genesis of the Form of 
the Fowl’s Egg (Proc. Amer. Philos. Soc., Vol. XX. XI. (1893), pp. 203-209) ; Wick- 
mann, H., Die Lage des Vogeleies im Eileiter vor und wihrend der Geburt (Journ. 
fiir Ornithologie, Vol. XLIV. (1896), pp. 81-92). 
2 Nathusius, W. v., Ueber die Eischalen von Aepyornis, Dinornis, Apteryx, ete. 
(Zeitschrift fiir wissensch. Zool., Vol. XXI. (1871), pp. 880-856) ; Ueber die char- 
acteristischen Unterscheidungszeichen verschiedener Straussen-eier (Journ. fiir 
Ornithol., Vol. XXIII. (1885), pp. 165-178) ; Hutton, F. W., On the Microscopical 
Structure of the Egg Shell of the Moa (Trans. New Zealand Inst., Vol. 1V. pp. 
166, 167), 1872. 
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