Physical Geography. 133 



and wing-cases of beetles and other insects, spiders, &c. 

 Earn pittings on the shales are not infrequent, together 

 with sun-cracks and footprints of Labyrinthodont 

 Amphibia, Dendrerpeton, Anthracosaurus, and other 

 genera. The rain pittings in this special case, tell of 

 showers falling on surfaces of moist mud, exposed by 

 the temporary retirement of fresh water, and the sun- 

 cracks of the drying and shrinkage of that mud ; and 

 these joined with the footprints of Amphibia tell of 

 daily events which by happy accidents got perpetuated, 

 first, by baking in the sun's rays. Next, when the area 

 was again overflowed, new layers of mud settled on 

 these impressions, and afterwards becoming consolidated 

 into shale ; and thus we have, in a measure, fossilised 

 sunshine, showers, and footsteps of old Amphibians, im- 

 printed, during their occasional visits to the moist land, 

 on the margin of the water in which they chiefly lived. 



Before closing the subject I must endeavour to 

 explain under what broad conditions of Physical 

 Geography the Carboniferous series was formed. 



It is impossible to have an intimate knowledge of 

 the Carboniferous rocks, even within the limited area 

 of the British Islands, without coming to the conclusion, 

 first, that the various strata were formed in seas, some 

 comparatively open and deep, some shallow, estuarine, 

 and restricted in area, and some .in fresh water ; and 

 second, that beds of coal were due to terrestrial vegetable 

 growths that flourished and died on the land, and were 

 buried with the soils on which they grew. To examine 

 all of these points in full detail would require the 

 writing of a special treatise, and I can here only glance 

 at the proofs. 



In the southernmost parts of South Pembrokeshire, 



