414 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [Mar. 14, 



for it is difficult to suppose that all these alternations of strata, and 

 the growth and accumulation of twelve distinct stages of vegetable 

 matter, could be otherwise than slowly effected. Comparatively 

 speaking, however, and so far as we know, its advent was towards 

 the close of the Carboniferous period. 



In the stratum of shale in which the first Lingulce were found, 

 there occur the remains of Fish, Entomostracans, and Plants, as well 

 as those of a species of Antliracosia, which are very numerous on one 

 horizon of the bed*". The piscine remains consist of Ganoid scales, 

 some of which are beautifully coated with brown enamel ; Sauroid 

 teeth resembling those of Holoptychius Hibberti ; and spines and iso- 

 lated bones. These remains are always in a detached state, — the 

 scales never being connected, nor the bones in juxtaposition. The 

 Entomostraca belong to two species, one of them bearing some simi- 

 larity to Gypris injiata, Murchison. The association of Entomostraca 

 with Fishes may, perhaps, assist in explaining the fragmentary con- 

 dition of the latter, as has been suggested before in a similar instance. 

 Among the vegetables is a small species of Lepidodendron, and appa- 

 rently a Sigittaria and a Catamites. On one horizon of the stratum, 

 the vegetable matter seems to form a layer of bituminous coal ; and 

 it is in this that the fish-remains are the most numerous. The Mol- 

 lusea and Entomostraca are not found in the coal, but only where the 

 stratum is more argillaceous. The Lingular and AnthracosicB, though 

 in the same stratum, are not associated. The remains of Fishes are 

 in close contiguity with the former ; and sometimes all the remains, 

 Lingular excepted, are to be seen on one plane, as though individuals 

 of the different species had lived and died together. In the grey and 

 more argillaceous shale above the first-mentioned bed, and where the 

 Lingulce are more common, the only other remains which occur are 

 a few Ganoid scales and bones of Fishes. 



It is not my intention at present to enlarge on the peculiar cha- 

 racter of this assemblage of species, further than to notice how the 

 occurrence of the Lingulce establishes the fact that marine conditions 

 must occasionally have prevailed in the Durham area during the 

 accumulation of the Upper Coal-measures. The discovery of L. 

 Credneri (an unquestionably marine shell) is, I believe, the first indi- 

 cation of marine conditions in this coal-field. Hitherto the Durham 

 Coal-measures have always been referred to as a series of freshwater 

 stratat, and pre-eminently lacustrine. It is therefore well we 

 should know that, though the general character of these measures is 

 decidedly lacustrine, or, rather, fluviatile, yet that in rare instances 

 there are intercalations of strata which contain marine remains. 



In commencing these remarks, the existence of other Carboniferous 

 species common to Permian rocks was generally alluded to. It may 



* I am informed by Mr. G. Tate, F.G.S., that in the monntain-limestone there 

 is a similar group of organisms in a shale connected with a coal-seam at Brunton 

 in Northumberland, where there are Lingulce squamiformis, Entomostraca, An- 

 tliracosia, remains of Ganoid Fish, and Plants. 



t See Lyell's ' Elements of Geology,' 4th edit. pp. 325, 326 ; and Phillips in 

 Encyc. Metrop., art. "Geology," p. 592. 



