I>LA.TE 1. 



Fig. 1. Productus latissimus; cast of interior of ventral valve, reduced to a 



little less than one-third diameter 354 



1 a. Outline profile of same. 



1 i. Surface-stria) of same, magnified. 



Fig. 2. Ath YRis subtilita ?, ventral view, reduced ia same way 355 



2 a. Dorsal view of same. 



Fig. 3. Spirifer keokuk ?, ventral view, reduced in same w&y 355 



3 a. Ventral view of a smaller individual, apparently of the same species, 



but proportionally shorter on the hinge-line ; reduced in same way. 

 Fig. 4. An undetermined bivalve, presenting the form and external appearance 

 ot a Mactra or Tancredia ; from New Castle Island, Nanaimo 

 group, reduced in size as above. 



4 a. Outline profile of same. 



Fig. 5. Undetermined bivalve from same locality and position as last, reduced in 

 same way. 



5 o. Profile outline of same. 



Fig. 6. IxocERAMUs ? Imperfect cast of a left valve, reduced in size as 



above 359 



The dim shading beyond the broken posterior and basal margins repre- 

 sents the restored outline. 



Note. — The figures on this and the following five plates were originally, in most ' 

 cases, drawn of natural size, and arranged for quarto plates ; but the whole were re- 

 duced for this'work to octavo size by photographs, from which the lithographer made 

 his tracing, and then finished the figures from the original drawings. 



