336 



C. LAPWOETH ON THE MOFFAT SERIES. 



Glossograptus Hincksii is represented by Glossograptus ciliatus (Emm.). 

 Dicranograpfcus ziczac ,, „ Dicranograptus furcatus (Hall ). 



Climacograptus Scharenbergi „ Climacograptus scalaris (His.). 



Clathrograptus cuneiformis „ Clathrograptus Geinitzianus (Hall). 



Thus, if the evidence from fossils be appealed to as indicative of 

 the geological age of the Glenkiln division, the facts already adduced 

 point unequivocally to a position in the Llandeilo formation as at 

 present understood. The complete absence of the Didymograpti of 

 the type of D. Murcliisoni, and of the genus Phyllograptus, so common 

 in the lower beds of that formation in Wales and Sweden, compels 

 us to assign it to the very highest division of the Llandeilo, imme- 

 diately at or not far below the base of the Caradoc or Bala. 



(b) Bala or Caradoc. 



The Upper Llandeilo age of the Glenkiln Shales having been thus 

 definitely settled, we naturally turn to the strata of the succeeding 

 Bala formation in search of the Graptolites of the Hartfell Shales. 



Unfortunately for our purpose, it happens that in Siluria and the 

 greater part of North Wales the rocks of this formation are of too 

 arenaceous a character to afford Graptolites. In one locality only 

 are they yet known to occur in comparative abundance, viz. in the 

 cliffs to the N.W. of the town of Conway, where Mr. Hopkinson has 

 collected * : — 





Corynoides calycularis (Mch.). 

 Dicranograptus ramosus (Hall). 



Nicholsoni (Hopk.). 



Dicellograptus Forchhammeri ( Gem.). 

 Morrisi (HopJc.). 



In Sweden the lowest beds of the Bala formation are represented 

 by the highest division of Linnarsson's Bicranograptus-schists, which 

 contains the following Hartfell species f : — 



Leptograptus flaceidus (Hall). 

 Diplograptus quadrimucronatus 

 (Hall). 



truncatus (Lapw.). 



foliaceus (Murch.). 



Dicellograptus Forchhammeri (Gein.). 



■ Morrisi (Hopk.). 



Dicranograptus ramosus (Hall). 

 Olingani (Carr.). 



Diplograptus foliaceus (Murch.). 



quadrimucronatus (Hall). 



Corynoides calycularis (Nich.). 

 curtus (Lapw.). 



In North America, as is well known, the higher Bala beds are 

 represented by the Lorraine and Utica Shales (Cincinnati Group) 

 that everywhere overlie the Trenton Limestone. They afford the 

 common Hartfell forms J — 



Leptograptus flaceidus (Hall). 

 Amphigraptus divergens (Hall). 

 Diplograptus foliaceus (Murch.). 

 truncatus (Lapw.). 



Dicranograptus ramosus (Hall). 



Nicholsoni (Hopk.). 



Diplograptus quadrimucronatus(-ffa^). 



None of the foregoing species have ever been met with in beds of 

 Lower Llandovery age, and only three or four in the Upper Llan- 

 deilo, viz. those species which are also common to the Glenkiln and 

 Hartfell Shales of Moffat. Thus the palseontological evidence of 



* Coll. Mr. Hopkinson. Compare also Mem. Geol. Survey, vol. iii. pi. xii.fig. 1. 

 t Coll. Dr. Linnarsson. 



X Nicholson (Collection) ; Hall, Grapt. Quebec Group, pp. 143, 144 ; Hall, 

 Pal. New York, vol. iii. Supp. fig. 509 ; Logan, Geol. of Canada, p. 200. 



