15,2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 57 



the phyllopod bed, as it contains a large, unique, and fine series of 

 phyllopod remains. It has a thickness of 7 feet, 7 inches, and is 

 capped by a layer of coarse, bluish, dirty-gray shale weathering 

 to a yellowish ochre-brown on the edges, that averages 18 inches in 

 thickness. The phyllopod bed may be subdivided as follows from 



the top downward: 



ft. in. 



1. Bluish-gray siliceous shale with partings of dirty gray-colored 



shale I 9 



2. Dirty-gray shale 8 



3. Bluish-gray shale in compact layers 3 to 4 inches thick i o 



4. Dirty-gray shale o 2 



5. Bluish-gray, tough, brittle shale o 2 



Great Eldonia ludwigi layer. 



6. Compact layer of bluish-gray hard rock that splits more or 



less evenly 8 



7. Alternating dirty and bluish-gray shale o 9 



Great Hymenocaris perfecta bed. 



8. The same character as No. 6: Compact layer of bluish-gray 



hard rock that splits more or less evenly o 8 



9. Dirty-gray, earthy shale 2 



10. The same character as No. 6: Compact layer of bluish-gray 



hard rock that splits more or less evenly i 4 



This is one of the most important fossil-bearing layers — 

 sponges, annelids, holothurians, and crustaceans. 



11. Dark, dirty-gray, earthy shale o 1.5 



12. Bluish-gray, tough, brittle shale o 1-5 



This is the great Marrella splcndens layer. 7 7 



Below No. 12 the layers of shale are arenaceous, irregular, and not 

 favorable for preserving fine fossils. 



In making the collections of 1910 and 1911 over 150 cubic yards 

 of rock were quarried and split up. Frequently, however, many 

 square feet of surface of the shale would be opened without exposing 

 a desirable specimen. 



Layer No. 12 is of great interest. It was a slab of this carried 

 down by a snow slide that Mrs. Walcott and I found in 1909 on the 

 trail from Burgess Pass to Summit Lake. It contains Marrella 

 splendens in great numbers, and of the annelids it has yielded the 

 only specimens of Miskoia preciosa and Amiskwia sagittiformis, and 

 most of those of Pikaia gracilens, Wiwaxia corrugata, and Canadia 

 spinosa. Among the crustaceans the only specimens of Opabinia 

 regaliSj Molaria spinifera, Yohoia tenuis, Y. plena, Mollisonia 

 gracilis, and M. f rara were found in it, and Burgessia bella, Waptia 



