AKT. 9 NEW CAMBRIAX CRUSTACEA — EESSER 3 



The Burgess shale locaKty in British Columbia, across the Pacific 

 Ocean from Manchuria, is too well Icnown to require any further 

 discussion of its geographic situation. 



The third locality is also in British Columbia, but many miles 

 south of Burgess Pass, between Fort Steele and Cranbrook. This 

 locality was first called to the attention of Dr. C. D. Walcott and some 

 of the fossils were collected by Col. H. Pollen, formerlj'^ of Fort 

 Steele. 



The fourth group of localities is also separated from the two in 

 British Columbia by the width of a continent. The two Pennsyl- 

 vania localities are only a few miles apart along the strike and hence 

 may be treated as one. Parkers Quarry in Vermont is another place 

 that has been known for many years having become famous when 

 Olenellus tJiom<psoni was described from it. While it has been known 

 for more than thirty years that the Mesonacid fauna was represented 

 in Pennsylvania, it has only been in the last decade that the fauna has 

 become well represented in the collections and the stratigraphic rela- 

 tions of the beds determined. 



STRATIGRAPHIC CORRELATIONS 



Relatively large collections, some of them brought together by 

 many years of intensive collecting, are on hand from each of the 

 regions described in the locality lists. Accordingly, we may assume 

 with reasonable confidence that the faunas are fairly represented in 

 our present collections. Yet taking the case of the Burgess shale 

 from which the largest collections (over 35,000 specimens) have been 

 obtained, as an example, w^e find that in spite of the intensive collect- 

 ing extending over a number of years, new forms are still found by 

 casual visitors to the outcrop. Strange to relate, all the Tuzoia 

 specimens, except the holotype, turned up only after two full seasons' 

 work. Keeping this example in mind we can the more readily 

 comprehend the likelihood of finding further material at any of the 

 places and thereby alter somewhat our present opinions of the exact 

 composition of the several faunas. 



The marvellous preservation of such a host of species in the Bur- 

 gess shale gives that fauna a definiteness that is scarcely equaled by 

 any other in the entire geologic column, even though its exact strati- 

 graphic position in the Middle Cambrian may not 3='et be precisely 

 fixed. The Burgess shale has usually been regarded as the exact 

 equivalent of the Ogygojisis shale member of the Stephen formation 

 which like this bed outcrops in only one restricted area — to the 

 south across the Kicking Horse Valley. But a close scrutiny of the 

 apparently identical faunas reveals the fact that many species for- 

 merly regarded as common to the two beds are really distinct, thus 



