2J 



466 MISS G. L. ELLES ON THE GRAPTOLITE [Aug. 1 898, 



1894. Of the more recent papers, the most complete is that of Marr, 

 who, utilizing palseontological evidence, divides the beds as 

 follows (Geol. Mag. 1894, p. 128) :— 



^(d) Milburn Beds = Uppermost Ai'enig or Lower Llandeilo. 

 (c) EUergill Beds. 



(h) Tetraffraptics-heds. | ^^^Z' ^^^ IHdymogra'ptus narms. 



^ ia) Bichograptus-hQdiS. 



1. JBrgographcs-heds. = Tremadoc Slates. 



1897. The following is the sequence adopted by the officers of the 

 Geological Survey in their recent memoir, ' Geology of the 

 Country between Appleby, TJllswater, and Haweswater ' 

 (p.34)t- 



5. Milburn Group. / Equivalents of the lower part of tbe 

 4. EUergill Beds. [ Borrowdale Series. 

 3. Upper Skiddaw Slates. 



2. Watch Hill Grits (Arenig Grit). 



1. Lower Skiddaw Slates and Grassmoor Grits. 



The rocks are regarded as the representatives of everythino- 

 between the Middle Cambrian and the Upper Arenig rocka 

 of Wales. 



{b) Palaeontological. 



1848. In 1848 Prof. Sedgwick described the earliest organisms 

 that were found in the Skiddaw Slates (Quart. Journ. Geol. 

 Soc. vol. iv, p. 223). These were two graptolites which 

 he referred to Graptolites Sagittarius (His.) and Gr. latus 

 (M'Coy), and four so-called fucoids. 



1863. 1^0 further additions were made till Salter gave a list in 

 his palaeontological appendix to Harkness's paper ' On the 

 Skiddaw Slate Series' (Quart. Journ. Geol. Soc. vol. xix 

 p. ]35). In this he gave a list of 17 species of graptolites, 

 and he also figm^ed some of the forms. Several of these 

 determinations were erroneous, due no doubt to the frag- 

 mentary condition of the specimens, and only a few of them 

 find a place in a modern list. 



1868. l^icholson's paper on ' The Graptolites of the Skiddaw Series ' 

 (Quart. Journ. Geol. Soc. vol. xxiv, pp. 125-145) was the 

 first systematic memoir on the fauna of these beds. The 

 descriptive part of it is exclusively devoted to graptolites, 

 which, as he justly remarks, form by far the most important 

 part of the fauna. He raised the number of species to 24 



(omitting several of Salter's), and the number of genera to 8 



Dicliograpsus, Tetragrapsus, Pligllograpsus, Bidymograpsus^ 

 Diplograpsus^ Pleurograpsus^ Grapttolites.^ and Dendro- 

 grapsus (?). 



The advance made in our knowledge of the graptolites in general 

 has affected many of the names and identifications adopted in that 



