Conveying ourselves, then, in imagination forward to the time when our greatest accumulations of coal were formed, and fancying that we are introduced to the American or European continent of that period, we find ourselves in a new and strange world. In the Devonian age, and even in the succeeding Lower Carboniferous, there was in the interior of America a wide inland sea, with forest belts clinging to its sides or clothing its islands. But in the coal period this inland sea had given place to vast swampy flats, and which, instead of the oil-bearing shales of the Erian, were destined to produce those immense and wide-spread accumulations of vegetable matter which constitute our present beds of bituminous and anthracite coal. The atmosphere of these great swamps is moist and warm. Their vegetation is most exuberant, but of forms unfamiliar to modern eyes, and they swarm with insects, millipedes, and scorpions, and with batrachian reptiles large and small, among which we look in vain for representatives of the birds and beasts of the present day. [Illustration: Fig. 33.--_Sigillariæ_, restored. A, _Sigillaria Brownii_. B, _Sigillaria elegans_.] [Illustration: Fig. 34.--_Sigillaria Lorwayana_, Dawson. _a_, Zones of fruit-scars. _b_, Leaf-scar enlarged, _c_, Fruit-scar enlarged. See appended note.] [Illustration: Fig. 35.--Stem of _Sigillaria Brownii_. reduced. Natural size.] [Illustration: Fig. 36.--Two ribs of _Sigillaria Brownii_.] [Illustration: Fig. 37.--Portion of lower part of stem of _S. Brownii_. Natural size.]