A. J. Jukes-Browne — Oji Rock- Classification. 295 



nition as a separate system, in the Pliocene." He thus constructs 

 three systems under the names of Eocene, Miocene, and Pliocene. 



I doubt, however, whether this suggestion is altogether commend- 

 able. The fact is that if marine invertebrata are taken as the 

 standard of measurement, there is only one Tertiary system, and in 

 that we are still living, for very few invertebi'ate genera have 

 become extinct since Eocene times. But if the vertebi'ates, both 

 marine and terrestrial, are taken into consideration, they afford 

 gi'ounds for making more than one system, though I doubt whether 

 the facts would sanction three as Dr. Blanford proposes. 



I agree with those who w^ould limit the number to two, though the 

 nomenclature proposed on the Continent is not likely to be adopted. 

 It appears to me that the existent names may be conveniently 

 retained without alteration or abstraction to represent the major 

 groups or series of the Tertiary systems, and that we have only to 

 find suitable names for the two systems into which they naturally 

 fall. British geologists would naturally prefer names taken from 

 their own country, and in this case it does not seem difficult to pro- 

 vide such names. Hampshire and the Isle of Wight affoi'ding the 

 most complete section of the Eocene and Oligocene, Hantonian 

 becomes an appropriate name for the system they would constitute. 

 In Britain the Falunian Miocene is absent, and we have only repre- 

 sentatives of the Pliocene and Pleistocene ; but the three may be 

 merged into a second system for which the name Icenian may be 

 revived,^ a name derived from the British, tribe of Iceni who inhabited 

 the eastern districts where the typical deposits of these groups are 

 found. For this plan I claim the merit of its not disarranging the 

 existing nomenclature, while it will prevent students from acquiring 

 an exaggerated idea of the geological importance of the Lyellian 

 groups. 



The accompanying table will show what systems appear to me to 

 be of nearly equivalent value on the principles above indicated, and 

 I may state that it has been drawn up for the purposes of a volume 

 on Historical Geology now in course of preparation. I wish, how- 

 ever, to ascertain whether the proposals it contains are likely to 

 meet with general approval, and shall therefore welcome criticism 

 from the readers of the Geological Magazine. Those who teach 

 our Science or prepare manuals for teaching purposes necessarily 

 feel the importance of having a consistent and well-proportioned 

 tabular view of the succession of strata, and yet they hesitate to 

 import new views and terms into their lectures and treatises because 

 the}' are expected to give only the accepted results of geological 

 study. 



A few remarks on this Table are necessary. In the first place, I 

 have avoided indicating the limits of the largest divisions or eras of 

 geological time, since there is so much difference of opinion as to the 

 precise boundary-line between the Palaeozoic and Mesozoic eras. I 

 must strongly protest against the tripartite division of everything 



1 This name was proposed by Dr. S. P. Woodward as a synonym for Pliocene in 

 his Manual of the JVlollusca, 1851. 



