SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



INTRODUCTION 



During the field season of 19 10 the study of the Cambrian strata 

 of the section of the Rocky Mountains adjacent to the main Hne of 

 the Canadian Pacific Railway was continued and special attention 

 given to the Stephen formation. Its outcrop was carefully exam- 

 ined for many miles along the mountain sides with the hope of 

 finding a locality where conditions had been favorable for (a) the 

 presence of life during deposition of sediments, (b) the subsequent 

 changing of sediments into rock, and (c) the preservation of the rock 

 during the vicissitudes consequent on m^ountain building, so that the 

 preservation of the life of Ae epoch would be as complete as possible. 

 The famous trilobite locality on the slope of Mount Stephen above 

 Field had long been known and many species of fossils collected 

 from it, but even there the conditions had not been favorable for 

 the presence and preservation of examples of much of the life that, 

 from what was known of older faunas and the advanced stage of 

 development of the Upper Cambrian fauna, must have existed in the 

 Middle Cambrian seas. The finding, during the season of 1909, 

 of a block of fossiliferous siliceous shale that had been brought 

 down by a snow slide on the slope between Mount Field and Mount 

 Wapta, led us to make a thorough examination of the section above 

 in 19 10. Accompanied by my two sons, Sidney and Stuart, every 

 layer of limestone and shale above was examined until we finally 

 located the fossil-bearing band. After that, for thirty days we 

 quarried the shale, slid it down the mountain side in blocks to a 

 trail, and transported it to camp on pack horses, where, assisted by 

 Mrs. Walcott, the shale was split, trimmed, and packed, and then 

 taken down to the railway station at Field, 3000 feet below. Among 

 the finds there were a number of specimens of a beautifully pre- 

 served Merostome which will be the subject of this paper, and the 

 first species to be described in a preliminary manner from the new 

 locality. 



