Viii ILLUSTRATIONS 



TO FACE PAGE 



31. Cambrian Trilobites (Crepicephalus) 244 



32. " " (Crepicephalus) 246 



33. " " (Crepicephalus) 248 



34. " " (Lonchocephalus, Saratogia, and 



Crepicephalus) 250 



35. " " (Crepicephalus, Saratogia, and Lon- 



chocephalus) 252 



36. " " (Lonchocephalus, Hanburia, Vanux- 



emella, Agraulos, Karlia, and Tsin- 

 ania) 254 



37. Cambrian Fauna (Lonchocephalus chippewaensis Owen and 



other species) 256 



38. " " (Wanneria walcottanus (Wanner)) 258 



39. Geologic map of area about Helena, Montana 262 



40. Unconformity between Cambrian and Pre-Cambrian in 



Grand Canyon 282 



41. " " Cambrian and Pre-Cambrian in 



Grand Canyon 284 



42. " " Cambrian and Pre-Cambrian in 



Grand Canyon 286 



43. " " Cambrian and Pre-Cambrian in 



Grand Canyon 288 



44. Middle Cambrian Brachiopoda from Park shale 300 



45. Cambrian Trilobites (Illmiurus and Mesonacis) 412 



46. " " (Bathyuriscus) 414 



47. " " (Bathyuriscus) 416 



48. " " (Bathyuriscus) 418 



49. " " (Bathyuriscus) 420 



50. " " (Bathyuriscus and Dolichometopus) . . 422 



51. " " (Dolichometopus) 424 



52. " " (Dolichometopus) 426 



53. " " (Dolichometopus) 428 



54. " " (Dolichometopus) 430 



55. " " (Corynexochus) 432 



56. " " (Corynexochus) 434 



57. " " (Corynexochus) 436 



58. " " (Asaphiscus zvheeleri Meek) 438 



59. " " (Asaphiscus) 440 



60. " " (Asaphiscus and Corynexochus) 442 



61. " " (Asaphiscus and Blountia) 444 



62. " " • (Asaphiscus CRlainia) ) 446 



