AET. 4 CAMBRIAN CONCHOSTEACA — ULRICH AND BASSLER 119 



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 Figure 32. Hipponicharion cavatum Matthew 63 



A right valve, X 4. 



Lower Cambrian (Hanfordian, C1B3): Hanford Brook, 

 New Brunswick. 

 33,34. Leper ditia ehenina Dwight 101 



Dwight's views of the type specimen of this species, 



X 2. 

 Middle Cambrian; Dutchess County, New York. 

 35. Leperdiiia veniricosa Matthew 100 



View, natural size, of the imperfect type of this species 

 and the surface ornamentation enlarged. 



Lower Cambrian (Hanfordian, C1J51): Hanford Brook, 

 New Brunswick. 

 36, 37. Beyrichona species. 



Front and edge views of two specimens X 6 described 

 by Cobbold as Escasona? species and introduced to 

 show occurrence of Beyrichona types in England 

 (after Cobbold). 



Lower Cambrian (Olenellus limestone) : Comley, 



(Shropshire), England. 



