INDEX 485 



PAGE 

 plicatella, see BiUingscUa. Orthis. and Plectorthis. 



Point Levis, Quebec, fossils at §5 



politiis, see Dicellomus. 

 Polyphemus, see Liiniilus. 



Polytcechia, compared with Clarkella and Syntrophia iii 



Polytocchia ? montanensis Walcott, mentioned as tj^pe of Clarkella iii 



Pompeckj, J. F., bibliographic references 114, 337 



Popes Peak, fossils from 319, 330 



Posterior region, defined 158 



Pre-Cambrian, unconformity with Cambrian in Alberta 426-427 



Pre-Cambrian life, absence of traces explained 252 



evolution of 252 



pretiosa, see Mickwitzia. 

 prima, see Bornemannia. 

 prima costata, see Acrothelc. 

 primava, see Acrotreta. 

 primcBVum, see Platyceras. 

 primordialis, see Syntrophia. 

 pristinus, see Trematobolus. 

 productus, see Bathyuriscus. 



Productus sp. undt., stratigraphic position and association 200 



proli£ctis, see Dicellomus. 



Proparia, genal spines of 237 



trilobite belonging to the order described 14-18 



Prospect Mountain, fossils from 322, 323, 345 



Prospect Mountain formation, defined 12 



fossils from 322, 32;^, 345 



history of use of term 12 



House Range, section of 184, pi. 17 



correlated 171 



Prospect Mountain limestone, Eldorado limestone proposed for 184 



Prospect Mountain quartzite, distinguished from Brigham formation of 



northeastern Utah 9 



Prospect Mountain sandstone, old formation name retained 184 



prospectensis, see Micromitra (Paterina). 



Protegulum, defined 158 



Protolenus fauna discussed 254 



Protospongia (spicules), stratigraphic position and association 194,209 



Protorthis, classification of 142, 147 



evolution of pi. 11 (pp. 140-141) 



Protorthis (Loperia), classification of 142, 147 



evolution of pi. 11 (pp. 140- 141) 



Protractor muscles, defined 157, 158 



Protremata, classification of 142 



defined 147, 158 



evolution of genera of pi. 11 (pp. 140-141) 



shell structure of Ordovician and Cambrian compared 151-153 



