HISTORY OF RESEARCH. 



CX1X 



1894. 



Marr, 



' Notes on the Skiddaw 



Slates," 'Geol. Mag.,' 



dec. 4, vol. 1. 



(2) 



An important paper, dealing with the range and distri- 

 bution of Graptolites in Britain, was published in 189-1 by 

 Marr, who gave a complete list of the Graptolites hitherto 

 found in the Skiddaw Slates. He divides the Skiddaw 

 Slates for the first time into the following horizons : 

 (d) Millburn Beds — Uppermost Arenig or Llandeilo (Lower). 

 {<•) Ellergill Beds, characterised by Didymog. fasciadatiis, Azygog. 

 ccelebs, T 'rigonograptus, etc. 



,,. ,„ ^ , ( Upper, with Didymog. nanus. 



(h) Tetragraptus Beds 1 T J 



J J l (-Lower. 



(a) Dichograptus Beds. 



(1) Bryograptus Beds = Tremadoc Slates. 



This paper and its zonal divisions formed the geological foundation for most 



of the subsequent graptolitic literature concerning the fossils of the Skiddaw Slates. 



In this paper the author figures from the Bryograjptus Beds specimens of 



Bryograptus ramostts and Bryo. Gallavei ?. 



I 894 - Hall, in 1894, published a more detailed account of the 



a ' ' ' Graptolite zones of Castlemaine. 



" Note oil the Distribu- TT . „ „ ,, ,. ,. „ ,. 



He argues m favour of the distinctness ot the genera 



Ooniograptus and Loganograptus, and points out that the 



auriferous bands of the colony begin above the base of the 



T. fruticosus zone, and range as high as the beds with Phyllo- 



graptus. 



Three letters dealing with the controversy on the 



terminology — Dictyonema or Dictyograptus — appeared in 



1894. 



In the first of these Lundgren considers that on the strict 



ground of priority Salter's name, Graptopora, should be substituted for Dictyonema, 



but thinks that it is unnecessary to adhere so rigorously to the laws of priority, 



and that in this case it would be mere pedantry to change a name so well 



established for a genus characteristic of so widespread an horizon. 



1894 - In the second, Moberg enters into the question in con- 



_. ° eu J' siderable detail, and replies to the arguments brought 



" Dictyonema contra 



tion of the GraptoHtidse 

 in the Rocks of Castle- 

 maine," ' Australian 

 Assoc, for the Advance, 

 of Science,' 



1804. 

 Lundgren, 



' Geol. Foren. F6rh.,' 

 bd. xvi, heft 4. 



Dictyograptus," ' Geol. 

 Foren. Fiirh.,' bd. xvi. 



1894. 



T'drnguiBt, 



" Dictyonema contra 



Dictyograptus," ' Geol. 



Foren. Forh.,' bd. xvi. 



forward, adopting " Hopkinson's name of Dictyograptus, on 

 the ground that I find it to be the oldest name in the list of 

 synonymies which is free from objections." 



The third and final communication on the subject was a 

 letter written by Tornquist, who confines himself to the 

 argument that the use of Dictyonema as the generic name of 

 both a plant and an animal is quite in accordance with the 

 rules laid down by the German Zoological Society. 



