660 
POPULAR SCIENCE .REVIEW. 
condensed from a liquid in the same way as the asphalte of the lake, accounts 
better than any other for its purity, seeing that “ all impure or foreign sub- 
stances which did not decompose would most likely be of greater specific 
gravity than the oil, and would naturally sink to the bottom.” The high 
state of preservation in which plants frequently occur in our coal-beds, and 
the fact of trees being found erect in them are easily accounted for upon 
this theory. Trees grow on the hardened pitch of the Trinidad lake within a 
short distance of other pitch which is in a state of ebullition, and one can 
readily conceive of the hardened pitch in any similar ‘case being softened by 
an eruption of the boiling pitch, and of the trees growing on it being thus 
engulfed, or of the lake overflowing its banks, and so submerging the sub- 
jacent vegetation. The new theory also furnishes an explanation of the 
exceeding tenuity of some coal-seams, which thin out into mere films over 
extensive areas of solid rock, and might easily be caused by an oily liquid 
having overflowed the rock when at the surface, and having in progress of time 
partly evaporated and partly solidified. The shape and dimensions of many 
other coal-seams are equally consistent with the idea of the seams in question 
being the solid residuum of what once were lakes of oil, and, indeed, the 
great majority of all coal formations are basin-shaped, “ with long and sloping 
sides dipping dovm to a common and profound centre,” a fact which certainly 
tells with great force in favour of the new hypothesis. 
An almost entire Skull of Rhinoceros leptorhinus has recently been found 
near Ilford, in Essex, and in close proximity to the spot where the skull and 
tusks of the mammoth secured last autumn for the “ National Collection ” 
were discovered. The head is nearly perfect, and is that of a rather aged 
adult, judging by the worn condition of the teeth, of which the whole series 
on both sides are preserved in situ. The fossil is not only interesting, as 
being the finest specimen of the species yet discovered in Britain, but 
also as afibrding conclusive evidence of its having been contemporaneous 
with Elephas primigenius. This specimen will probably enable palaeontolo- 
gists to determine with certainty the species of rhinoceros to which the limb 
and trunk bones belong that are found intermixed with those of the mam- 
moth ox, horse, &c., in the Ilford beds, and which are of far more slender 
proportions than those of Rhinoceros tichorhinus.See Geological Magazine^ 
July. 
Fossil Wood in Flint. — An interesting specimen of this kind, which is in 
the Oxford Collection, has lately been described and figured in a paper by 
Professor Phillips. The nodule of flint, which when broken across disclosed 
the contained wood, was of an elongated oval form, and had the uneven and 
knotted surface which frequently indicates aggregation on a sponge. The 
fractured surface showed partial change of colour by watery action from 
without, and many variations of tint within, arising from some original 
difierences in the composition of the mass. The colour was, on the whole, 
somewhat lighter than is common in flints of the “Upper Chalk.” Examined 
with a lens, it showed traces of spicula and other organic bodies ; but it was 
impossible to trace through the mass a distinct spongy structure. The wood 
lay in the centre, and the figure of the flint was,dn a general sense, -conformed 
to it, and embraced it equally on all sides. There was a certain distinctness 
of colour in the flint where it lay in contact with the wood. The wood was a 
