Page:Popular Science Monthly Volume 68.djvu/252

248 and easily floated by rains into streams and rivers, and thence carried by currents into larger bodies of water, where permanent deposits are accumulating. Both wings and molts are fairly resistant to decay, and thus more readily preserved than are the softer parts of the body. Such molts have been found in this country from the Coal Measures at Mazon Creek, Illinois; from the Upper Coal Measures of Eastern

Kansas; and from the Permian of Central Kansas. Recently an interesting specimen, shown in the accompanying illustration, has come to light from the Coal Measures of Clinton, Missouri. A few specimens have also been obtained from the coal formation of Scotland. The young of Paleozoic cockroaches closely resemble the adults, and were evidently in form and habits very similar to young cockroaches of the present day.

The cockroaches of Carboniferous time are, on a general average, larger than those of later time. The largest described form, Archoblattina Beecheri Sellards, has a body, exclusive of the head, three and one half inches long, with an expanse of wings of six and one fourth inches. The Permian forms, and, also, those from mesozoic and later formations, are, so far as known, smaller than those of the Carboniferous.

There appears to be no authentic record of the occurrence of