NO. 5 UPPER CAMBRIAN TRILOBITES RESSER II3 



PLATE 4 



PAGE 



Irvingella alberta, new species 23 



1-3. Dorsal, front, and side views of the holotype cranidium (X2). 

 Lyell formation; (loc. ipu) Johnson Creek, 8 miles east of Lake 

 Louise, Alberta. 



Irvingella richmondensis, new species 23 



4-6. Dorsal, front, and side views of the holotype cranidium (X6). 

 Secret Canyon shale; (loc. 60) near Richmond Mine, Eureka District, 

 Nevada. 



Irvingella adamsensis, new species 24 



7-9. Side, dorsal, and front views of the holotype cranidium (X2.5). 

 10, II. Front and dorsal views of a larger cranidium (X i-5)- 

 Secret Canyon shale; (loc. 60) near Richmond Mine, Eureka District, 

 Nevada. 



Irvingella flohri, new species 24 



12-14. Front, side, and dorsal views of the holotype cranidium (X3)- 

 Secret Canyon shale; (loc. 60) near Richmond Mine, Eureka District, 

 Nevada. 



Parairvingella etirekensis, new species 26 



15-17. Dorsal, front, and side views of the holotype cranidium (X3)- 

 Secret Canyon shale; (loc. 61) south of Hamburg Mine, Eureka Dis- 

 trict, Nevada. 



Parairvingella angustilimbata Kobayashi 26 



18-20. Two dorsal, front, and profile views of a complete cranidium 



(X2). 



21, 22. Side and dorsal views of the holotype cranidium (X i-S)- 

 Secret Canyon shale; (Iocs. 62, 63) north of Adams Hill, Eureka 

 District, Nevada. 



Parairvingella harnhurgensis, new species 27 



23, 24. Dorsal and side views of the holotype cranidium (X2). 

 Secret Canyon shale; (loc. 61) south of Hamburg Mine, Eureka Dis- 

 trict, Nevada. 



Parairvingella intermedia, new species 27 



25-27. Dorsal, front, and side views of the holotype cranidium ( X 3 ) • 

 28, 29. A larger cranidium (X2). 

 30, 31. Large incomplete cranidium (X i-5)- 



Secret Canyon shale; (loc. 61) south of Hamburg Mine, Eureka Dis- 

 trict, Nevada. 



Drumaspis idahoensis, new species 29 



32-34. Dorsal, front, and side views of the holotype cranidium (X2). 

 35. 36. Another, less complete cranidium (X2). 



St. Charles limestone; (loc. 4y) Two Mile Canyon, 2 miles south of 

 Malad, Wasatch Mountains, Idaho. 



Drumaspis walcotti, new species 28 



37-39. Dorsal, side, and front views of the holotype cranidium (X 5)- 

 40, 41. A larger cranidium (X3)- 



St. Charles formation; (loc. 4y) Two Mile Canyon, 2 miles south of 

 Malad, Wasatch Mountains, Idaho. 



Irvingella tuniifrons ( Hall and Whitfield) 25 



42, 43. Dorsal and front views of the holotype cranidium (X i-S)- 

 Secret Canyon shale; Pogonip Mountain, White Pine District, Nevada. 



