OF THE FOSSIL PLANTS OF THE COAL-MEASURES. 
519 
have been deposited in the cavity left as the result of the manducatory efforts of 
the animals. Their variation in size is obviously also a result of corresponding 
variations in the Zylophagi, whilst their uniform granular structure is explained by 
their origin. These copros are exactly like those of the phytophagous larvae of recent 
insects; but beyond this probable association of them with insect forms, I discover 
no grounds for arriving at a more definite identification. 
In 1874, Count Castracane announced to the Academia del Nuovi Lincei, at Rome, 
that after subjecting pulverised coal to a process of combustion and afterwards to the 
action of certain chemical reagents, he not only found the siliceous frustules of Diatoms 
in the residual ash, but that many of these Diatoms were of well-known living species. 
The coals thus operated upon were derived from near Liverpool, from Newcastle, and 
from the French coal-field of St. Etienne. This discovery, if real, possessed an obvious 
importance. Hence its verification or the reverse became very desirable. My colleague, 
Professor Roscoe, kindly allowed Mr. Smith, one of his able assistants, to subject 
numerous specimens of coal to Count Castracane’s process. The coals thus experi¬ 
mented upon were the following Yorkshire and Lancashire ones :— 
Bradford Better bed. 
Worsley Binns. 
,, Roof of Cannel. 
,, Cannel. 
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33 
33 
33 
33 
33 
33 
33 
33 
„ Base of bed. 
Fourfoot. Top of seam. 
Black. 
Dow. 
,, Bottom of seam. 
„ Top of seam. 
Brassey. 
,, Roof of coal. 
Trencherbone. Top layer. 
,, Middle coal. 
White. 
Roof of coal. 
,, Yard. 
Middleton (Yorkshire) Main. 
,, ,, Settle Black. 
„ ,, Adwal. Top of Cannel, 
,, „ Main. Top of coal. 
Australian coal. Three samples. 
The result of these investigations was to obtain a series of preparations of coal-ash 
3x2 
