NOETHTTMBEUIAND AND DtrEHAM. 13 



Limestone southward of the Stublick Dike with the northern 

 beds in iN'orthumberland, as the physical characters of the two 

 series are so different, and because, moreover, the organic con- 

 tents of the southern beds are imperfectly known. In addition to 

 the fossils already noticed I have seen the following, from lime- 

 stone and shale, at Stanhope : Terelratula hastata ; Rhynchonella 

 pleurodon; Athjris ambigiia ; Spirifer integricostatus, odoplicatus, 

 gldber ; Plearotomaria altaviUa ; Bellerophon striatus ; Dentalium 

 priscum. The beds, in this part of our district, have, however, 

 been divided into two groups ; those above the Whin Sill, from 

 the Tyne bottom to the Eell Top Limestone, have been referred 

 to the Toredale series of Philips, and those below the Sill to the 

 Scar Limestone of that author ; but this division seems arbitrary, 

 and is not yet supported by organic remains ; and it would more- 

 over apply to a limited area only. It would not apply to the 

 northern series ; for the "Whin Sill, though intruded into the cal- 

 careous division of that group, and generally among the higher 

 beds, has no definite place among them — indeed, it cuts through 

 them, and we find its relative vertical position among the strata 

 varying to the extent of 1000 feet. 



Throughout the whole of the Mountain Limestone fossil plants, 

 identical with those found in the Newcastle Coal Measures, or ana- 

 logous to them, occur in the sandstones and shales, and even in 

 the coal itself. The following species are a few of those which 

 have been noticed : Araucarites carlonarius ; Stigmaria ficoides, 

 veiy abundantly ; Sigillaria organa, Lepidodendron Harcourtu, 

 ohovafum, aculeatum, Sterniergn, selaginoides, gracile, anglicum, 

 &c. ; TTlodendron ornatissimum; Knorria imbricata; taxina; Cala- 

 mites SiicTcowii, cannceformis, &c. Perns, so abundant in the Coal 

 Measures, are rare in this group ; in a few localities Sphenopteris 

 Johnstoniana has been found, a species allied to >S^. gracilis. 



Of our modern Flora a few plants in ^Northumberland are pecu- 

 liar to the limestone, such as Sesleria ccsrulea, Potentilla verna, 

 Spircea filipendula, and Saxifraga tridactylites. A few others, 

 though not entirely confined to limestone soils, rarely grow 

 elsewhere, such as Scabiosa columharia, Viola hirta, Plantago 

 media. 



