202 THE CARBONIFEROUS SYSTEM. 



we visited Cumberland during the time represented by one of the 

 groups of coals, bituminous limestones, and erect forests, we should 

 have beheld vast swampy plains covered with dense forests, calamite 

 brakes, and peaty bogs, intersected by sluggish streams and shallow 

 lagoons. Had we visited it perhaps some centuries later, at the time 

 when one of the barren groups of sandstone was being deposited, the 

 eye would have ranged over a wide and shallow sea, filled with sand- 

 banks, and with occasional low islets and spits, covered with Siglllariae 

 and fringed with wide borders of Calamites, struggling for existence 

 among the shifting sands. Changes of this kind alternated again and 

 again, while the whole area was constantly subsiding at a rate so slow, 

 that mechanical deposition and animal and vegetable growth were able 

 to a great extent to counteract and sometimes altogether to neutralize 

 its influence. At length, however, in the Upper Coal formation, 

 aqueous conditions regained a decided preponderance. This, then, be 

 it borne in mind, was the process employed by the great Architect 

 of the universe in building up the Coal-fields of Nova Scotia and of 

 the world ; and we are indebted to the clean and sharp section effected 

 by the tides of Chiegnecto Bay for that fine exposure of its stony 

 monuments which enable us to understand and explain in such detail 

 its nature. 



Remains of Aquatic Animals in the Coal Measures. 



I propose in the .sequel to devote an entire chapter to the land 

 animals of the Coal formation. In the present note, I desire to state 

 some interesting facts in regard to the remains of aqicatic animals 

 which abound in the shales and bituminous limestones, associated 

 with plants, and without any intermixture of brachiopods, corals, or 

 other absolutely marine productions. Though I do not consider these 

 creatures as fresh-water animals, yet they must be regarded as the 

 tenants of brackish, and perhaps sometimes fresh, ponds, lagoons, and 

 creeks of the Coal formation swamps, and which must have been, for 

 the most part, shallow, land-locked, and filled with putrid vegetable 

 matter, though no doubt often at the sea level, and communicating 

 with it by channels more or less wide. 



I. Bivalve Shells. — All the Lamellibranchiate shells, which are so 

 numerous in some of the shales and bituminous limestones of the 

 Joggins that some of the beds may be regarded as composed of them, 

 belong to one generic or family group. They are the so-called 

 Modiolas, Unios, or Anodons of authors. I proposed for them, some 

 years ago, the generic name of Naiadites, and described six species 

 from the Coal measures of Nova Scotia, stating my belief that they 



