viii
ILLUSTRATIONS
| 23. | Middle Cambrian Annulata (Canadia and Aysheaia) | 144 |
| 24. | Middle Cambrian Crustaceans (Neolenus, Ptychoparia, Mollisonia, and Tontoia) | 208 |
| 25. | Middle Cambrian Crustaceans (Marrella) | 210 |
| 26. | """ (Marrella) | 212 |
| 27. | Middle Cambrian Crustaceans (Burgessia, Waptia, and Opabinia) | 214 |
| 28. | Middle Cambrian Crustaceans (Opabinia, Nathorstia, and Naraoia) | 216 |
| 29. | Middle Cambrian Crustaceans. (Molaria, Habelia, and Yohoia) | 218 |
| 30. | Middle Cambrian Crustaceans (Bidentia, Emeraldella, and Burgessia) | 220 |
| 31. | Middle Cambrian Crustaceans (Hymenocaris and Leanchoilia) | 222 |
| 32. | Middle Cambrian Crustaceans (Hymenocaris, Fieldia, and Hurdia) | 224 |
| 33. | Middle Cambrian Crustaceans (Carnarvonia and Tuzoia) | 226 |
| 34. | """ (Hurdia, Odaraia, and Anomalocaris) | 228 |
| 35. | Brachiopods and Trilobites (Lingulella, Obolus, and Ceratopyge) | 236 |
| 36. | Trilobites (Olenopsis) | 248 |
| 37. | Cryptozoon proliferum Hall | 280 |
| 38. | Trail of Annelid (Climactichnites) | 282 |
| 39. | """ (Climactichnites) | 284 |
| 40. | """ (Climactichnites) | 286 |
| 41. | Potsdam-Hoyt Fauna (Lingulella, Triblidium, Pelagiella, and Matherella) | 288 |
| 42. | Potsdam-Hoyt Fauna (Matthevia) | 290 |
| 43. | """ (Palæacmæa, Hyolithellus, Hyolithes, Lonchocephalus, Agraulos, Ptychaspis, and Ptychoparia) | 292 |
| 44. | Potsdam-Hoyt Fauna (Dikelocephalus, Conokephalina, Pagodia, and Ptychoparia) | 294 |
| 45. | Legs of Trilobites (Neolenus serratus) | 296 |
| 46. | Tracks of Trilobites (Protichnites) | 298 |
| 47. | """ (Protichnites) | 300 |
| 48. | """ (Protichnites) | 302 |
| 49. | """ (Protichnites) | 304 |
