I9II.] STEVENSON— FORMATION OF COAL BEDS. 87 



peat; paper peat, which is a bituminous clay with infusoria; Blatter- 

 kohle, a marly clay with a little sedimentary peat. 



Pelagochthonous types are : ( i ) Normal Carboniferous coal fields. 

 The coal beds have originated from floating forests and remains of 

 rooted trees occur in very limited localities. Naumann's paralic 

 coal-fields belong here; they are found in America, China, etc. (2) 

 Sea basin deposits, consisting of limited but often very thick beds, 

 the coal frequently thinning seaward ; these contain, besides sylvo- 

 marine remains, abundant remains of trees rooted in clay. Best 

 seen in France. Here, in part, Naumann's limnic basins. (3) 

 Amorphous anthracite, consisting of the finest detritus and forming 

 irregular deposits; does not include Faser-, Staub-or Koksanthracite 

 coal. 



Penhallow*^ has given the results obtained by study of cannel- 

 like coal from the lower Alesozoic of British Columbia. All the 

 samples are composed of rod-like bodies more or less closely com- 

 pressed, which resemble dark amber and are embedded in a cement- 

 ing material. The rods show tubules within, many of them branch- 

 ing, which are very suggestive of Mycelium; granulations are com- 

 mon and often form zones around hyaloid areas. The features 

 revealed by the microscope are : 



(i) Absence of structure, (2) tubular ramuli of diverse dimen- 

 sions, (3) rounded cavities, (4) large proportion of material in 

 angular fragments and resembling that of the rods, (5) an amor- 

 phous substance, associated with (4), occurring as distinct flakes or 

 as cement to unite the rods. 



Appearance of structure was observed in only one rod and in 

 that case it is evidently due to shrinkage; he thinks the spore-like 

 aggregations are of chemical rather than of organic origin. The 

 general character of the ramuli at once suggest Mycelium, but the 

 intimate features and the arrangement forbid reference to vegetable 

 structure. They rather resemble effects of internal shrinkage, fol- 

 lowing hardening of the outer layer, such as one sees in amber and 

 other resins. The material occupying spaces between the rods and 



*° D. P. Penhallow, " A Preliminary Examination of So-called Cannel 

 Coal from the Kootanie of British Columbia," Amcr. Geologist, X., 1892, pp. 

 331-339- 



87 



