Dr. Mac Culloch on the Lignites, 215 



fossil vegetables has referred them to terms rather than genera, 

 under the names of carpolithes, phyllites, lycopodiolithes, palma- 

 cites, endogenites, fyc. ; nor is it here necessary to quote the more 

 minute distinctions under which it has been attempted to divide 

 and arrange them. The fossil animal remains, accompanying 

 them, have been noticed by so many writers, that it is unnecessary 

 to give a list of them. 



The last division of the lignites is that which occurs in alluvial 

 soils, and which seems necessarily limited to the more ancient 

 alluvia. The scattered specimens, of various character, dispersed 

 in the upper or alluvial parts of the tertiary or fresh-water strata, 

 must be ranked in this division, but we are not well furnished with 

 recorded examples of this nature. I must follow the prevailing 

 opinions, in referring the well-known case of Bovey to this di- 

 vision, though by no means satisfied that it is a real instance of an 

 alluvial lignite. For want therefore of satisfactory observations, 

 we can only conjecture generally what the characters of such a 

 deposite ought to be, and what are the accompanying substances. 

 It is to be suspected that, though Bovey should be a real example, 

 many of the supposed alluvia, containing amber and jet, described 

 by authors, are rather cases of the tertiary strata beneath ; and 

 that perhaps the sands of the plastic clay, or other portions of 

 these deposite s, have been mistaken for alluvial formations. 



There is another difficulty respecting the descriptions of the 

 alluvial lignites, lying at the opposite extreme. Among the nu- 

 merous examples of forests submerged under alluvial soils, it is 

 not often that observers have inquired whether the wood possessed 

 the characters of lignite, or was simply in the state in which the 

 wood of peat-bogs is found, namely, little changed from its ori- 

 ginal condition, or else partially converted into peat. In other 

 cases, however, it has been ascertained that the wood was de- 

 ranged in form, or flattened, as if from the consequence of great 

 pressure ; while, at the same time, it exhibited those peculiar 

 chemical properties by which the lignites are distinguished from 

 peat. In such situations it has been found that the lignite varied 

 in quality, or in the degree in which it had undergone the change 



