QUEBEC GROUP. 35 



the general black or dark color. In Newfoundland the Levis division consists of 

 graptolitic shales, having a thickness of 4,000 feet, which are followed by about 

 1,000 feet of serpentines and diorites referred to the Lauzon division; and these by- 

 black slates and limestones, having a thickness of 4,000 feet, referred to the Sillery 

 division. Serpentines, diorites, and slates sound like Upper Taconic, and it may 

 be undiscovered faults have given rise to an erroneous determination of the order, 

 and therefore the so-called Lauzon and Sillery may be below the Levis; or it may 

 be an erroneous identification of the Lauzon and Sillery; and yet the true solution 

 may be found in the fact that all three divisions belong to the Upper Taconic, for 

 the trilobites described by Billings, from these rocks in Newfoundland, have a 

 primordial or Taconic aspect. The author has never had an opportunity to 

 examine the rocks of the Quebec Group, but an examination of the present state 

 of the learning respecting it, makes it very doubtful whether or not the name 

 should be retained. If the Group belongs to the Taconic System, as most of it 

 undoubtedly does, possibly the name should be retained. If that part of it in the 

 East from which Calciferous fossils have been obtained, constitutes all of it except 

 that which belongs to the Taconic, then probably the name should be stricken from 

 Lower Silurian nomenclature, and the part containing such fossils should be included 

 in the Calciferous Group, in which event the Chazy Group would include some of 

 the rocks referred to the Quebec in the Western mountains, and the rest would 

 belong to the Upper Taconic. 



§ 68. The Quebec Group has been recognized in the Wahsatch Eange, in Utah, 

 at Pogonip Mountain, Nevada, and other places in the Western mountain chains, 

 where the Calciferous and Chazy have not been distinguished from it. In the Pog- 

 onip mountain-beds the following species are said to pass from clearly distinguished 

 beds of the Potsdam Group up three or four thousand feet into as certainly de- 

 termined beds of the Quebec Group, viz. : Lingxdepis maera, L. minuta, L. manticula, 

 Acrotreta gemma, Agnostus communis, A. bidem, A. neon, Qrepicephalus haguei, and 

 C. unisvlcatus. 



§ 69. In this Group we find the first illustration of an important branch of the 

 animal kingdom reaching its highest stage of development, and subsequently de- 

 clining, and finally becoming extinct. The first known Oraptolites appear in slates 

 of the Upper Taconic System, and reach the climax of evolution in the Quebec 

 Group, and become extinct in the Upper Silurian era. The development 

 of these forms seems to have been wonderful. About thirty genera have been 

 distinguished in America, and to these have been referred about 170 species. The 

 Group is said to be connected specifically with higher Groups by Maclurea atlantica 

 and Asaphus canalis, that occur in the Chazy, and by Leptcena sericea, which is com- 

 mon to all the Groups in some of its varietal forms as high as the Clinton. 



§ 70. This Group is said to graduate up into the Chazy without lithological 

 lines of separation, and without an abrupt break in the chain of fossils. Clear pas- 

 sage-beds occur where the Groups are well developed, and even where there is non- 

 conformability some fossil species are said to be common to the two Groups. The 

 geographical surface distribution is confined to limited areas east of the Appalachian 

 System, and to small exposures among the Western chains ; but it must represent a 

 vast period of time, as evidenced by the great development and evolution of its 

 animals, and by the erosion of the Calciferous where it does not exist. 



