HL 
quarry in Dumfriesshire, impressions of the feet of 
small animals of the tortoise kind, having four feet, 
and five toes on each foot. They were seen in various 
layers through a thickness of forty feet or more. 
Sandstone, in which these impressions are princi- 
pally discovered, is a rock composed chiefly of siliceous 
and micaceous particles cemented together by calca- 
reous or argillaceous paste, containing salt, and colored 
with various shades of the oxide of iron, particularly 
the red, gray, brown. It has been remarked by Prof. 
H. D. Rogers, that the perfection of the surface con- 
taining fossil footmarks is often attributable to a 
micaceous deposit. The layers of sandstone have been 
formed by deposits from sea-water, dried in succession ; 
such layers are also seen in the roofing slate. These 
deposits on the shores of the ocean, having in a soft 
condition received the impressions of the feet of birds, 
other animals, vegetables, and also of rain-drops, 
under favorable circumstances dried, hardened, and 
formed a rock of greater or less solidity. Our col- 
league, Dr. Gould, has exhibited to us a specimen of 
dried clay from the shores of the Bay of Fundy, 
containing beautiful impressions, recently made, of 
the footsteps of birds. The particles brought by the 
waves, and deposited in the manner described, were 
derived from the destruction of other rocks previously 
