NO. 12 SPENCE SHALE AND ITS FAUNA RESSER 29 



Plate 6 



PAGE 



Byfhichciliis fypiciiin, new species 22 



Fig. I. Complete individual and cranidium (X i-S)- 



Fig. 2. Individual lacking libragenes (X2.5). 



Fig. 3. Holotype (X2). 



Fig. 4. Small example (X3). 

 Clappas.pis spencei, new species 20 



Fig. 5. Exfoliated cranidium. 



Fig. 6. Partially exfoliated holotype (X2). 

 Clappaspis lanata, new species 20 



Fig. 7. Holotype (X i-S). 

 BythlchcUiis alvcatum, new species 22 



Fig. 8. Exfoliated cranidia (X2.5). 



Fig. 9. Exfoliated conventionally lighted cranidium (X2). 



Fig. 10. Holotype (X2.5). 

 Clappaspis coriacea, new species 20 



Fig. II. Cranidium. 



Fig. 12. Holotype cranidium (X2). 

 Clappaspis dotis, new species 21 



Fig. 13. Cranidium, with Spencia plena (X2). 



Fig. 14. Holotype (X2). 

 EIrathia spencei, new species 18 



Fig. 15. Holotype (X2). 



Fig. 16. Smaller individual retaining libragenes (X2). 



Fig. 17. Exfoliated specimen (X2). 

 EIrathia rara, new species 19 



Fig. 18. Holotype (X2). 

 Spencia plena, new species 23 



Fig. 19. Partially exfoliated holotype cranidium (X3). 



Fig. 20. Small cranidium (X3). 



Fig. 21. Cranidia with Bythicheihis alvcatum (X2). 

 Spencia typicalis. new species 23 



Fig. 22. Cranidium showing granules (Xi-S)- 



Fig. 23. Small cranidium (X i-S)- 



Fig. 24. Holotype (X2). 



Fig. 25. Cranidium (X lo)- 

 Clappaspis idahoensis, new species 20 



Fig. 26. Holotype. 



Fig. 27. Two smaller individuals. 

 Ehmaniclla qnadrans (Hall and Whitfield) 19 



Fig. 28. Original type of cranidium (X 2.5). 



Fig. 29. A less distorted cranidium (X3)- 



Fig. 30. Associated libragene (X2.5). 



Fig. 31. Pygidium (X3)- 



Locality 20x. 



Fig. 32. Limestone nodule with cranidia and fragments of pygidia. 



Locality 55e. 



