710 ME. J. E. MAEK AOT) DE. H. A. NICHOLSON 



part of it, and Cyrtograptus Grayce, especially, occurs ia such vast 

 abundance in one seam at the very top of the crispus-h&di&, that we 

 have thought fit to allude to this seam especially as the Grayce-hoj^idi. 



Our comparison of the Stockdale Shales with the Birkhill and 

 Gala groups renders unnecessary a minute comparison with the 

 similar Grraptolitic deposits in other areas. Such a comparison has 

 already been successfuly instituted by Prof. Lapworth in his papers 

 on the " Geological Distribution of the Ehabdophora " and on " The 

 Moffat Series." 



We merelj^ proceed to add a few supplementary remarks, and in 

 the first place call attention to some researches of the late Dr. 

 Tullberg, published since the appearance of the above-mentioned 

 papers of Prof. Lapworth. By Dr. Tullberg's early death science 

 has been deprived of a most promising Graptolithologist and strati- 

 graphical geologist, and his co-workers have lost a genial companion. 

 In a paper *' Om Lagerfoljden i de Xambriska och Siluriska Afla- 

 gringarne vid Eostanga " * he suggests the following correlation of 

 the beds of Scania and Scotland : — 



BracMopod-sMffer with Fhacops mucronatus, 

 Brongn. = Lower BirkhiU ? 



Lohiferus-sJciffer. = Upper BirkhiU ; 



and divides the latter as follows : — 



Shales with Monograptus spinigerus, Nich,, "^ 

 Biplograptus {Fetalo.) cometa, Gein., M. gre- \ C Zone of M. gregaritis. 

 garius, Lapw., M. cyphus, Lapw., M. Sandersoni, )■ = \ „ „ ^- cometa. 



Lapw., Bastrites peregrinus, Lapw., Climaco- j [ „ „ M.. 

 graptus normalis, Lapw., &c. ) 



Shales with Bastrites maximus, not foxmd in = Zone of Bastr. maximus. 

 Scania. 



Betiolites-sJciffer. 



Shales with Monograptus crispus &c. = Gala and Grieston. 



The latter succeeded by 



Shales with Cyrtograptus Murchisoni &c. = Wenlock. 



A fuller comparison is made by the same author t in a paper 

 published in 1882. At the summit of the beds which he describes 

 as appertaining to the Lower Silurian group or Ordovician, he places 

 a dark-grey shale with DipIog7r(jL)tus, n. sp., and Climacograjjtus 

 scalaris, Lapw., and an absence of Monograptus. This succeeds the 

 zone of Phacops mucronatus, Aug., and most probably represents 

 our zone of Diplograptus acuminatus. The Hastrites-heds are placed 

 at the base of the (Upper) Silurian and are divided as follows : — 



At the base is the zone of Monograptus cyphus, containing also a 

 DimorpTiograptus. We shall presently give reasons for concluding 

 that this represents our zone of DimorpTiograptus confertus. 



* Geol Foreningens i Stockhobn Forhandl. 1880, No. 59, Bd. v. No. 2. 

 t " Skanes Graptoliter : Part I.," Sveriges Geologiska Undersokning, Ser. 0, 

 no. 60. 



