JONES — TRACKS, TRAILS, AND SURFACE-MARKINGS. 137 
with water. The eggs themselves are sold in cakes in the market, 
pounded and cooked, and also in lumps au naturel, forming a sub- 
Fig. 10. — A piece of the dried clay bed of a pond in Kent, a, a, ova of boat-flies (?) ; 
b, b\ b", galleries, with raised roofs, made by water-insects ; c, c, furrow, made by 
a water-insect, crossing the footprint (.r) at d ; at c the furrow' enters a gallery, of 
which the I'oof has been broken; at /"it becomes a tunnel or gallery, with convex roof, 
such as seen also at b, b ; g, g, small galleries ; h, J>, furrows ; i, i, holes ; k, k, shell 
of a Lhnnceus ; m, a furrow-track. 
stance like the roe of a fish. This is known by the characteristic 
name of ' ahuauhtl,' that is, ' water-wheat.' " 
The occurrence of the eggs of insects in the Mexican travertine, 
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