259 



phanus Loganianus, Pleuromya suhcompressa, Astarte Fackardi, Trigatiia 

 Dawsoni, Grammatodon inoniatus, Camptonectes extenuatus and Grijplwiici 

 Nehrascensis) hold also Modiola (or Volselld) formosa o^ Meek and 

 Hayden, and GervUlia Montanaensis of Meek. 



The discovery in the Black Hills of Dakota of deposits which wore 

 supposed to be of Jurassic age, principally upon palteontological grounds, 

 was tirst announced by Mr. F. B. Meek in 1858, and since that time 

 numerous species of fossils from rocks of a similar geological horizon 

 in Utah, Montana and other Western States and Territories, as well as 

 in California, have been desci'ibed by Mr. Meek, Professoi- E. P. Whit- 

 field and Dr. C. A. White. 



The reasons which induced Mr. Meek to regai'd certain strata in Utah 

 and Dakota as Jurassic are clearly stated on pages 110 and 111 of 

 Dj-. Hayden's " Geological Eeport of the Exploration of the Yellow- 

 stone and Missouri Rivers" and elsewhere, but the conclusions at 

 which Mr. Meek ai-rived, with the somewhat meagre material at 

 his disposal, although such as any paleontologist would probably have 

 come to under the circumstances, appears to the writer to be outweighed 

 by the additional evidence afforded by the large collection of fossils 

 since made by Mr. Eichardson and Dr. Dawson at the Queen Charlotte 

 Islands and on the mainland of British Columbia, which throw an 

 entirely new light on the subject. 



Throughout the Western States these supposed Jurassic rocks arc 

 everj^where stated to occupy a jjosition immediately below the sand- 

 stones and conglomerates of the " Dakota Group " (which Meek main- 

 tains is the equivalent of the English Upper Green Sand) and as 

 immediately above certain red beds which are generally believed to be 

 Triassic. Wherever these ostensibly Jurassic rocks occur, therefore, 

 it follows that part of the Mesozoic series is wanting, and it is difficult 

 to understand why the Lowei- Cretaceous and earlier half of the Middle 

 Cretaceous should always be missing and not the Jurassic. 



As will be seen a little ftirther on, there are good reasons for 

 supposing that the Agglomerates and Lower Sandstones of the Queen 

 Charlotte Islands form part of the same formation as the Lower 

 Shales, but, whether this be the case or not, the thi'ee together occupy 

 almost exactly the same stratigraphical })Osition as the supposed 

 Jurassic rocks of the Western States. At Oumshewa and Skidegate 

 Inlets the Lower Shales immediately vinderlie conglomerates which 

 are pi-obably synchronous, or nearly so, with those which almost 

 invariably occur at the base of tlie " Dakota Group," and the Lower 

 Sandstones are succeeded by Upper Triassic rocks, although the two 

 latter are unconformable. 



Turning next to the palajontological aspect of the question, Mr. 



