ARGILLACEOUS SCHIST. 361 



This catalogue might easily be extended, as 

 the varieties of mixture and aspect are very great ; 

 but it has been limited to those which are most 

 conspicuous for their extent and frequency within 

 the limits of my observation, namely, in Scot- 

 land, Wales, and Cumberland. It comprises 

 the coarse graywackes and graywacke schists of 

 mineralogists, and these rocks have generally 

 been enumerated in the transition class. 



When the fragments become materially in- 

 creased in size, such rocks would more naturally 

 claim a place among conglomerates; and it is 

 obvious that these varieties bear the same relation 

 to the finer argillaceous schists that the conglo- 

 merates do to ordinary sandstone. They might 

 perhaps be conveniently classed under a 



FIFTH DIVISION. 



Argillaceous conglomerates. 



The varieties to be ranked under this title, if 

 adopted, need not be specified, as they would 

 merely be repetitions of the preceding catalogue. 

 The only distinction, to the collector of sped- 



