1862.] HARKNESS SKIDDAW SLATE SERIES. 135 



dant. The exposure of the Skiddaw slates at Black Comb also shows 

 that the south-west margin of the area of the older palaeozoic rocks 

 has likewise been subjected to great denudation. 



As concerns the age of the Skiddaw slate series, the sequence of 

 the strata above it, its position, and also its depth below the Coniston 

 limestone would lead to the inference that it occupies the horizon of 

 the Llandeilo flags ; and the fossils corroborate this conclusion. 

 Mr. Salter has already pointed out the affinity of these fossils to 

 those of the lower portion of the Llandeilo series* ; and in a note he 

 informs me that the Skiddaw slates are referable to " that group 

 which is best represented in the rocks of Shelve, and which occurs in 

 North Wales overlying the Tremadoc group, and underlying the mass 

 of the Llandeilo, — a series containing the earliest and most varied 

 forms of Graptolites, and which is at once the birth-place and metro- 

 polis of the family, as nowhere else are there so many g\nera or such 

 complex forms." This evidence, combined with the sequence of the 

 rocks in the Lake- district, distinctly places the Skiddaw slate series 

 on the horizon of the Lower Llandeilo, and also places the Quebec 

 group of Sir William Logan, as suggested by Mr. Salter, in the same 

 position. 



Note on the Skiddaw Slate Fossils. By J. W. Salter, Esq., F.G.S., 

 A.L.S., of the Geological Survey of Great Britain. 



The persevering labours of Prof. Harkness have been again rewarded. 

 But little was known, notwithstanding the old explorations by Prof. 

 Sedgwick, of the fauna of the Skiddaw slates till within the last 

 three years, when, at my request, Mr. Bryce Wright took advantage 

 of a short residence each year near Skiddaw to search for organic 

 remains in what proves to be a rich formation. The Museum in 

 Jermyn Street and the Cambridge Museum have received, since 

 that time, many accessions through Mr. Wright's labours. The 

 fauna proved to be of a newer date than had been assigned to it in 

 Prof. Sedgwick's table of classification : not, indeed, relatively to the 

 other rocks of the Lake -district, for the Professor has put it in its 

 right place with respect to them ; but instead of being, as suggested, 

 an equivalent of the great formation of the Lingula -flags, its fossils 

 indicate it to be of the age of some part of the Llandeilo-flags ; and 

 I shall endeavour to show that it must be the lower portion of that 

 formation. 



Two species of Graptolites and some imperfect remains (considered 

 as sea- weeds by Prof. M'Coy) were the fossils known to Prof. Sedgwick 

 at the time of the publication of his great work in 1851 f. 



Mr. Wright fortunately discovered at least six more Graptolites, 

 and a Crustacean with a curious, elongated carapace of two valves, 

 which I shall here term Caryocaris (fig. 15), as it has long wanted 

 a name. An obscure figure of it appeared in the ' Geologist ' of 

 February 1861, together with a figure of the most remarkable of the 



* ' Geologist,' vol. iv. p. 74. 



f ' Synopsis of the Classification of the Pakcozoic Fossils in the Woodwardian 

 Museum. ' 



