38 



by Professor Phillips, was also made known about the same time. 

 In the preceding year, 1847, Mr. John Ruthven of Kendal was 

 sent into the neighbourhood of Keswick by Professor Sedgwick, 

 for the purpose of ascertaining whether the Skiddaw Slate Rocks 

 were really fossiliferous or not. He had a tent pitched on 

 Skiddaw, near the White Stones, and he continued working there 

 for a week or more. I endeavoured to obtain an account of that 

 expedition, and its results, but failed to do so. I believe, however, 

 that Mr. Joseph Graham of Keswick had the honour of being the 

 first to discover Graptolites in the Skiddaw Slates, and in all 

 probability it was to test the genuineness of his discoveries that 

 Mr. Ruthven was engaged in 1847. 



There are about two hundred and fifty species of British 

 Graptolites known, and of these forty have been found in the 

 Skiddaw Slates. They consist of leaf-like, or branching, grass-like 

 bodies, or the impression of those bodies, left in the stone in which 

 they have been enclosed. There is much variety of form amongst 

 them, although all bear the common family likeness in their 

 general structure. Those fossilized forms are the remains of 

 chitinous or horny cases once inhabited by composite organisms, 

 or they may be described as colonies of semi-independent creatures; 

 which, when living, must have had a very marked resemblance, in 

 many points, to the Sertularian Zoophytes that inhabit our seas 

 at the present time. Their general form consisted of one or more 

 rows of horny cups or cellules, attached to a tube or common 

 canal, into which they probably opened by a narrow aperture at 

 their bases. The common canal was also composed of the same 

 horny substance. Generally the whole structure called the 

 " polypary," was based upon a slender rod of the same material, 

 which often projected beyond both ends of the common body, in 

 young members, but the distal prolongation was less frequent in 

 those of mature growth. 



Each portion of the polypary fulfilled its own office. The rod 

 that formed the foundation or back-bone of the structure is called 

 the "axis" (Fig. 3) ; it consisted of a slender fibrous cylinder, 

 extending along the side of the common canal, opposite that on 



