AET.4 CAMBRIAN CONCHOSTRACA — ULRICH AND BASSLER 111 



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Figure 12. Bradona perspicator (Matthew) (see also pi. 1, figs. 6-9) 24 



12. A left valve, X 4. 



12 1. Matthew's type specimen A, X 2, showing aspect 



when unwhitened. 

 Lower Cambrian (Etcheminian E2o) : Dugald Brook, 

 N. S. (13d"). 



13. Bradoria obesa (Matthew) (see also pi. 1, fig. 27) 27 



Photograph of the type specimen, X 5, of Bradoria 



vigilans mut. obesa Matthew. 

 Lower Cambrian (Etcheminian, E16) : Dugald Brook, 

 Nova Scotia. 

 14, 15. Bradoria cambrica (Matthew) (see also pi. 1, fig. 10) 28 



14. A right valve, X 5. 



15. A left valve, X 5, differing slightly in outline from 



the typical form. 

 Lower Cambrian (Hanfordian, Protolenus zone, 

 C163): Hanford Brook, New Brunswick (2i). 



16. Bradoria nitida (Wimsin) 31 



A right valve, X 8 (after Wiman) . 

 Cambrian: Aland, Sweden. 



17. Bradoria fennicus {Wiman) 30 



A left valve X 7 (after Wiman). 

 Cambrian; Aland, Sweden. 

 18,19. Bradoria vigilans concentrica, new variety 17 



18. An incomplete right valve, X 4. 



19. A right valve, X 4, showing particularly the more 

 nearly vertical third of the anterior margin. 



Lower Cambrian (Etc heminian, E3d) : Dugald 

 Brook, Nova Scotia (13m). 



20. Bradoria tontoensis, new species 24 



The unique right valve upon which this species is 

 founded, X 4. 



Middle Cambrian: Bright Angel shale. Grand Can- 

 yon, Ariz. 



21. Beyrichonaf rutellum (Matthew) (see also pi. 1, fig. 32)__ 48 



The t3'pe of Escasona rutellum Matthew, X 2, un- 

 whitened, and showing the aspect of these Crusta- 

 cea in the rock. 



Lower Cambrian (Etcheminian, E3/) : Gillis, Indian 

 Brook, Nova Scotia. 



