126 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



graphical or on palseontological grounds, the beds being everywhere 

 conformable and of nearly similar lithological aspect, while most of 

 the characteristic fossils are found throughout. The upper beds of 

 the series, however, are more shaly, softer, and darker in colour than 

 the lower, whilst the peculiar genera Dicliograpsus and Tetragrapsiis 

 do not seem to be represented in them, and there is a slight admix- 

 ture of Upper- Llandeilo types. 



When the Skiddaw Slates were first studied by Professor Sedgwick, 

 two Graptolites, and some obscure tracks (the so-called *■' fucoids ^') 

 constituted all their known organic remains ; and the group was 

 therefore considered by him the probable equivalent of the Long- 

 mynd or Cambrian Formation (see Synopsis Brit. Pal. Poss. Intro- 

 duction, p. xxi). Since then, however, and mainly by the researches 

 of Prof. Harkness, we have become acquainted with a large, if not 

 very varied, fauna from the Slates, and we are thereby enabled to 

 refer the entire group with certainty to the age of the Lower 

 Llandeilo rocks. At home the Skiddaw Slates have no positive 

 equivalent, but abroad they find an unquestionable representative in 

 the Quebec group of Canada. 



The fossils of the Skiddaw series include a large and remarkable 

 group of Graptolites, and a few remains of animals higher in the scale 

 of creation. These latter comprise a common Phyllopod crustacean, the 

 Caryocaris Wmghtii, a new Phacojjs which Mr. Salter has done me 

 the honour to name P. Nicholsoni, Agnostus Morel, JEglina hinodosa, 

 and fragments apparently belonging to a large Ogygia. A D'lsciaa. 

 is mentioned (Cat. Possils in the Jermyn Street Museum) as occur- 

 ring at Skiddaw ; and I have likewise found a small Lingula, of 

 not uncommon occurrence, considered by Mr. Davidson to be 

 L. hrevis. Lastly, there occur numerous Annelid-buiTows, and 

 worm-tracks, to which may be referred the PaJceocTiorda major, 

 P. minor, and Chondrites acutangidus of M'Coy, all properly belonging 

 to the genus Helminthites of Salter (Mem. Geol. Survey, vol. iii.). 

 The great bulk, however, of the organic remains of the Skiddaw 

 Slates consists of Graptolites ; and the remarkable point about these 

 is their close resemblance to, and in many cases specific identity 

 with, the Graptolites of the Quebec group of America, which have been 

 so ably described, and so beautifully illustrated by Prof. James Hall 

 (Geol. Survey of Canada, Decade ii.). The Skiddaw GraptoKtes have 

 been briefly noticed by Mr. Salter (Quart. Journ. Geol. Soc, vol. xix. 

 p. 185), who gives a list of fourteen species as then known to him. 

 Some of these I have found it necessary to omit; but the materials now 

 in my hands enable me to raise the total number of species to twentj-, 

 belonging to six genera, and forming a peculiar and unique assem- 

 blage. As regards their distribution they may be divided into three 

 groups. The first of these comprises forms which are entirely con- 

 fined, as far as we yet know, to this particular horizon, and which 

 are referable to the genera Dichograpsus, Tetragrapsus, and Pliyl- 

 lograpsus. In America various other genera belong to this section, 

 which have not hitherto been found in Britain. The second division 

 comprises species belonging to the cosmopolitan genera Diplo- 



