248 New York State Museum 



vey (among them Walcott '85, '86, '90, '91, '12, '15, 

 '08-'22). The Cambrian section of northwestern Ver- 

 mont is discussed in Keith ('23). 



Among the bulletins of the New York State Museum 

 are Miller ('24), in which will be found numerous 

 references, Gushing ('05a) and Miller ('17). For the 

 Cambrian, Dale ('04), Ruedemann ('30), Gordon 

 ('11), Berkey and Rice ('21), Holzwasser ('26) may 

 be consulted, and other references will be found in 

 these bulletins. For the Ozarkian are suggested Cush- 

 ing ('05b) Ulrich and Cushing ('10), Cushing and 

 Ruedemann ('14) and Chadwick ('20). Then for clas- 

 sification of New York formations there is Hartnagel 

 ('12). 



Canadian and Ordovician Periods 



The rocks of Ordovician age in Wales were classed 

 by Sedgwick as a part of the Middle and the whole 

 of the Upper Cambrian, but Murchison made the type 

 of his Lower Silurian rocks of the same geological age 

 in South Wales. The Silurian system was divided in- 

 to two parts by Murchison (1835), which were called 

 the Lower and Upper Silurian, a classification that is 

 followed by some even to the present day. Some fol- 

 lowed Sedgwick, others Murchison and it was not un- 

 til after the proposal by Professor Lapworth (1879) of 

 the name Ordovician for the Lower Silurian that geol- 

 ogists in general came to an agreement. The name 

 was taken from the Ordovices, an ancient Celtic tribe 

 which at the time of the Roman conquest occupied 

 the territory now included in northeastern Wales and 

 the adjoining parts of England. Great Britain, Swed- 

 en, Norway, Denmark and the United States have ac- 

 cepted this classification, but in other European conn- 



