106 THE STOEY OF THE EAETH AND MAN. 



music of living things that geology as yet reveals to 

 us ; and this, not by the hearing of the sound itself, 

 but by the poor remains of the instrument attached 

 to a remnant of a wing from the Devonian shales of 

 New Brunswick. 



A remarkable illustration of the abundance of cer- 

 tain plants in the Devonian, and also of the slow and 

 gradual accumulation of some of its beds, is furnished 

 by layers of fossil spore-cases, or the minute sacs 

 which contain the microscopic germs of club-mosses 

 and similar plants. In the American forests, in 

 spring, the yellow pollen-grains of spruces and pines 

 sometimes drift away in such quantities in the breeze 

 that they fall in dense showers, popularly called 

 showers of sulphur; and this vegetable sulphur, 

 falling in lakes and ponds, is drifted to the shore 

 in great sheets and swathes. The same thing appears 

 to have occurred in the Devonian, not with the pollen 

 of flowering plants, but with the similar light spores 

 and spore-cases of species of Lepidodendron and 

 allied trees. In a bed of shale, at Kettle Point, Lake 

 Huron, from 12 to 14 feet thick, not only are the 

 surfaces of the beds dotted over with minute round 

 spore-cases, but, on making a section for the micro- 

 scope, the substance of each layer is seen to be filled 

 with them; and still more minute bodies, probably 

 the escaped spores, are seen to fill up their interstices. 

 The quantity of these minute bodies is so great that 

 the shale is combustible^ and burns with much flame. 

 A bed of this nature must have been formed in 



