INDEX 
439 
World’s Scarcest Crinoids, by C. 
Keyes, 76 
Worthen, A. H., cited, 36, 134, 308 
Wyville-Thomson ridge, 194 
Yai^e University, mentality, 54 
Yorkic Period in Stratigraphy, by 
C. Keyes, 243 
Yorkic Period, suggested, 234 
Yung, M. B., cited, 208, 386 
Zinc, first mention in America, 340 
Zorritos formation of Equador, 22; 
Peru, 22 
Zuni Crater, 87 
