GRAPTOLITES OF THE SKIDDAW SLATES. 



By J, POSTLETHWAITE, F.G.S, 



(Read at the Ambleside Meeting.) 



The name Graptolite, or Graptolithus, is derived from two Greek 

 words — GraJ>ho, I write, and Lithos, stone. It was first made use 

 of by Linnaeus, in describing a fossil of a somewhat doubtful 

 character, but which bears a strong resemblance to the family of 

 Graptolites. A drawing of this fossil, which was called by Linnxus 

 Graptolithus scalaris, appeared in a work published by him in 1 75 1. 

 It appears, however, to represent not one, but three distinct organ- 

 isms, and their identity with any known species has not been 

 clearly established. Linnaeus also described a well known Grapto- 

 lite, which he named Graptolithus Sagittarius. 



I believe Sir Roderick Murchison was the first English author 

 who wrote on these fossils. In his Silurian System, published in 

 1839, is figured three species, namely, Graptolites ludensis, 

 G. viurchisotii, and G. foliaceus, and he was among the first to 

 recognise the importance of Graptolites as Silurian fossils. 



General Portlock, in his Geological Report on LondondeiTy, 

 Tyrone, and Fermanagh, published in 1843, noticed their affinity 

 to the Hydroid Zoophytes. He regarded them as being very 

 nearly allied to Sertularia (Figs, i and la) and Pluraularia (Fig. 2) 

 which are to be found in large numbers on our coasts. 



In 1848 Professor Sedgwick announced that Graptolites had 

 been found in the Skiddaw Slates; and the discovery of these 

 fossils in the south of Scotland by Mr. Salter, and in North Wales 



