C. LAPWOETH ON THE MOFFAT SERIES. 335 



forms, it may be inferred that this band of dark shale and there- 

 fore the Glenkiln Shales themselves are of the Upper or highest 

 Llandeilo age. 



This inference is greatly strengthened by the facts obtainable in 

 the Llandeilo strata of Central Sweden, where the greater portion of 

 the Llandeilo formation of Britain is represented by the well-known 

 Orthoceras-Limestone. Upon this limestone reposes the sheet of 

 dark shales denominated by Dr. Linnarsson * the Middle Graptolitic 

 Schists. The lowest beds of this deposit, which, according to Torn- 

 quist, are most intimately associated with the underlying limestone, 

 afford abundant examples of Phyllograptus and the MurcJiisonifoxm 

 species of Didymograptus. These, however, soon disappear, and the 

 highest beds that can be satisfactorily assigned to the Llandeilo for- 

 mation afford the strikingly peculiar Glenkiln forms : — 



Didymograptus superstes (Lapw.). I Cliinacograptus Scharenbergi (Lapw.). 

 Coenograptus gracilis (Hall). | perexcavatus (Lapw.). 



But it is on the continent of North America that we meet with 

 the most complete representatives of the Glenkiln Shales. The dark 

 shales and flagstones that bound the valley of the Hudson in the 

 neighbourhood of the city of Albany were originally assigned by 

 American geologists f , on imperfect data, to the Lorraine and Utica- 

 Slate formation (Cincinnati Group), which everywhere overlies the 

 Trenton Limestone. Their geographical position, their perfect 

 agreement in rapid convolution and amount of alteration with the 

 neighbouring Quebec (Taconic) Eocks, together with the compara- 

 tively ancient facies of the small group of fossils they afford, force us 

 to regard them rather as forming the highest division of the so-called 

 Quebec Group, whose greatly disturbed beds are believed by Professor 

 Sterry Hunt J and others to emerge unconformably from below the 

 horizontal Trenton Limestones. On this view the Hudson-River 

 Shales stand in the place of the higher Llandeilo beds of Britain. 



At Norman's Kiln, in the Yalley of the Hudson, on the Marsouin 

 Eiver, on the Lower St. Lawrence, and elsewhere they yield Grap- 

 tolites in some abundance. Prom the figures and descriptions of 

 Professor Hall the palaeontologist can easily identify the following 

 Glenkiln species § : — 



Dicellograptus sextans (Hall). 



divaricatus (Hall). 



Coenograptus gracilis (Hall). 



surcularis (Hall). 



Dicranograptus ramosus (Hall). 

 Diplograptus tricornis (Carr.). 

 Whitfieldi (Hall). 



Diplograptus foliaceus (Murch.). 



angustifolius (Hall). 



Climacograptus bicornis (Hall). 

 Thamnograptus typus (Hall). 

 Didymograptus serratulus (Hall). 



■ superstes (Lapw.). 



Corynoides calycularis (Nich.). 



Even the peculiar Glenkiln species absent from these American 

 strata are represented by intimately allied forms. Thus : — 



* Linnarsson, MS. Compare also Dr. Tornquist, OSfVers. af K. Vet.-Akad. 

 Forhandlingar, 1871. 



t Emmons's Amer. Geol. vol. i. p. 47. 



X Hunt, ' Chemical and Geological Lectures.' 



§ Prof. Hall, ' Paheont. New York,' vol. i. pis. 72 and 73, vol. iii. pp. 495 

 et seq. ; Grapt. Quebec Group, p. 54. 



