1941] 
Antiquity of Social Insects 
51 
Brown’s paper) shows a series of dome-shaped projections, 
arranged in rows ; these are regarded by Dr. Brown as casts 
of the cells of the nest . 2 The counterpart of the fossil is lined 
by shallow cavities which fit over the ends of the projections. 
One portion of this counterpart also has projections like 
those on the other half, so that when the parts of the con- 
cretion are placed together, the dome-shaped projections 
extend inwards from both sides. This extraordinary con- 
dition, which is not mentioned by Dr. Brown, seems to re- 
quire an explanation, if the specimen is regarded as a nest. 
The method by which a wasp nest might be preserved so 
as to resemble the fossil in question is very difficult to ima- 
gine. Dr. Brown has concluded that the specimen rep- 
resents part of a papery nest like that of Polistes, but he was 
apparently unable to explain to his own satisfaction the 
process of preservation, for he left “to the reader the pleas- 
ure of speculating as to the circumstances and method by 
which the original comb became this fossil.” It seems clear 
that in order to have a nest so preserved, particles of sand 
and mud must have filled the cells and become cemented to- 
gether while the walls retained their shape. Then, since there 
is no part of the actual nest remaining, its substance must 
have been replaced by additional sand and mud, as it dis- 
integrated. In this way a cast of the nest or of a portion of 
it would be formed. This process of preservation, involving 
two steps, seems to be inevitable, and it is indicated by the 
lithology of the fossil, for the sand particles forming the 
casts of the “cells” differ in size and other details from those 
replacing the “cell” walls. What seems impossible to us is 
that the paper nest would retain its shape long enough to 
allow the filling in the cells to become so hard that it would 
hold its form after the disintegration of the paper walls. If 
a paper comb of any living genera of social wasps (i.e., 
Vespinse, Polybiinse, Polistinse, Ropalidiinse) were buried 
and filled with sand and mud, the thin soft walls between the 
cells would, in our opinion, inevitably disappear within a 
short time, long before the foreign material could harden. 
We have not, of course, experimented with a nest to deter- 
mine how long it could hold its shape under such conditions ; 
2 Dr. Brown refers to the fossil as a viould, but we consider the term 
cast more appropriate. 
