624 



INDEX. 



Yoldia, iii, 403 



Yorktown formation, iii, 260 

 Young, C. A., cited, ii, 542 

 Yukon river, delta of, i, 202 

 Yule limestone, ii, 154; iii, 571 



Zamia, iii. 39 

 Zamites, iii, 39, 173 



pennsylvanicus, iii, 41 



yorkensis, iii, 41 

 Zaphrentis centralis, ii, 525 



gibsonii, ii, 616 



gigantea, ii, 463 



ponderosa, ii, 462 



Zaphrentis, Silurian, ii, 407 



umbonata, ii, 406 

 Zaptychius carbonaria, ii, 528 

 Zechstein, ii, 628 

 Zeiler, R., cited, i, 652; ii, 591; 



iii, 41 

 Zeolites, i, 428, 467 

 Zeuglodons, Eocene, iii, 239 

 Zinc, in Illinois, ii, 337 



in Iowa, ii, 337 



in Missouri, ii, 337 



in Ordovician, ii, 337 



in Wisconsin, ii, 337 

 Zircon, i, 467 



Zittel, K. von, cited, i, 658, 659; 



"»4i3 

 Zone of accommodation, ii, 130 

 Zone of fracture, i, 219, 427 

 Zones, climatic, migration of, 



Pleistocene, iii, 486 

 Zonites priscus, ii, 611 

 Zonitoides minusculus, iii, 410 

 Zoological provinces of Cam- 

 brian life, ii, 292 

 Zurcher, P., (and Bertrand,) 



cited, iii, 252 

 Zygospira exigua, ii, 356 

 recurvirostris, ii, 356 



