On the Coal-field of Sutherland. 45 



also appear to lie in the upper beds of this part of the deposit. 

 They form a different set of calcareous strata ; but the animal 

 exuviae are frequently intermixed in the same stratum with 

 the carbonaceous matter vvhich appears to have been derived 

 from vegetables. The species of organic substances which I 

 had an opportunity of examining, are far from numerous; and 

 they are so very often obscure, from being mutilated and im- 

 bedded in an unusually compact limestone, that it was impos- 

 sible to determine all their species, if indeed they are all to 

 be found ainong,^t)^se.\^l}iql^, n^tuj^U^^s^ in, t^ jlepartment 

 have ascertained, ,^,^,J^,^ \,,.,^'^^^^:^^^ ^'^l/.!rfi^ 



In the genus ammonites, five or six well marked species, 

 vith a probability, from impressions and fragments, of there 

 being even two or three more. Two gryphites. Two, or perhaps 

 more, belemnites. Many apparent fragments of spiral uni- 

 valves ; and two, which prove to belong to turritella and nerita. 

 Also a buccinum. Among bivalves, species in the genera 

 pecten, modiola, plagiostoma, terebratula, mya, ostrea, trigo- 

 nia, cardium, and apparently some others, which, from the im- 

 perfection and small number of my specimens, were unassign- 

 able. Besides these, I find abundance of the spines of echini, 

 some flustrse, some joints of encrini, and other fragments which 

 seemed to surpass all powers of analysis. I need not be more 

 minute, as the purposes of geology, such as I view that 

 science, are accomplished, as far as my purposes are concerned, 

 by this enumeration. The question of extinct zoology is of a 

 far different nature : but I see no necessity for confounding 

 them ; and this does not form the present pursuit. As to the 

 vegetable fragments, it is abundantly easy to describe forms, 

 and stripes, and much more : but I have not discovered to 

 what this tends, where the remains are so very obscure as they 

 are here, or as I at least find them. ,J 



After leaving these calcareous strata, the strata which succeed 

 consist of various shells and sandstones, with occasional small 

 laminae and larger beds of coal, and some thin and partial beds 

 of sand, apparently resulting from the decomposition of some 

 of the most friable sandstones. It would be quite fruitless to 

 attempt to describe the order of succession in these repeated 

 alternations ; since they present every where that irregularity 



