Mr Tate on a Sea Star, &c. 73 



the layers above and those below it, there are many fragments 

 of carboniferous plants of the genera Sigillaria, Lepidoden- 

 dron, Culamites, Knorria, and the Stigmaria ficoides. These 

 cases prove, I think, that some of the sandstones of the 

 mountain limestone of Northumberland vrere deposited in 

 shallow bays of the sea in which marine organisms lived, and 

 into which were drifted plants which grew during the carbon- 

 iferous era. These facts, however, do not invalidate the con- 

 clusion, that coal was formed of plants which grew on the 

 places where coal beds are now found ; for even in the North- 

 umberland mountain limestone formation, each coal seam 

 rests on an under-clay, which was the muddy and probably 

 swampy soil on Avhich the carboniferous flora grcAv ; some- 

 times a limestone with marine fossils overlies a coal seam, 

 but we never find a limestone with marine fossils lying be- 

 low it. 



As even minute facts carefully observed, help to illustrate 

 the geological history of the coal era, I may briefly notice two 

 other beds which show changing conditions during the period 

 of their deposition. At Budle, there is a metamorphosed 

 shale, about 30 feet in thickness, near to the basaltic 

 whin sill, and overlying a limestone. Now, in the under 

 layers of this bed, there are numbers of marine organisms, 

 such as the trilobite Griffithides Farnensis, the molluscs, 

 Eumphalus carbonarius, Bellerophon Urii, decussatus and 

 striatus, Leda attenuata, Posodonia Becheri, Strophomena 

 crenistria, Chonetes Hardrensis, Lingula squamiformis, &c. ; 

 but, as we ascend upward, a stray fragment of a plant ap- 

 pears mingled with these organisms ; one of the plants is an 

 endogenous leaf, on which is the marine annelid Spirorbis 

 carbonarius ; further upward, the plants increase and the 

 marine organisms decrease ; and, in the upper part of the de- 

 posit, the marine organisms disappear, and between the layers 

 of shale there are many fragments of carboniferous plants 

 such as Stigmaria ficoides, ferns of the genus Sphenopteris, 

 Bechera, and leaves of endogenous plants. 



In Berwickshire, into which the mountain limestone is 

 prolonged in a narrow band along the coast, there is a simi- 

 lar bed, in which occurs the entomostracan Estheria striata, 

 var. Tateiana. The lower layers contain Chonetes Hardren- 

 sis, and Nucula gibbosa; but, in the upper layers, there are 

 Sphenopteris Johnstoniana, Coniferites verticillatus, and reed- 

 like stems, on which are species of Spirorbis; and, besides 

 these, there are the teeth and scales of Holoptychius Hib- 



