Ch. V.] THE TERTIARY EPOCH. 53 



We may sometimes prove, that certain strata belong to the 

 recent period by aid of historical evidence, as parts of the delta 

 of the Po, Rhone, and Nile, for example; at other times, by 

 discovering imbedded remains of man or his works ; but when 

 we have no evidence of this kind, and we hesitate whether to 

 ascribe a particular deposit to the recent era, or that immedi- 

 ately preceding, we must generally incline to refer it to the 

 latter, for it will appear in the sequel, that the changes of the 

 historical era are quite insignificant when contrasted with those 

 even of the newest tertiary period. 



Neiver Pliocene period. This most modern of the four 

 subdivisions of the whole tertiary epoch, we propose to call the 

 Newer Pliocene, which, together with the Older Pliocene, con- 

 stitute one group in the annexed tables of M. Deshayes. 



We derive the term Pliocene from vXsiav, major, and x/vor, 

 recens, as the major part of the fossil testacea of this epoch are 

 referrible to recent species*. Whether in all cases there may 

 hereafter prove to be an absolute preponderance of recent 

 species, in every group of strata assigned to this period in the 

 tables, is very doubtful; but the proportion of living species, 

 where least considerable, usually approaches to one-half of the 

 total number, and appears always to exceed a third ; and as our 

 acquaintance with the testacea of the Mediterranean, and some 

 other seas, increases, it is probable that a greater proportion 

 will be identified. 



* In the terms Pliocene, Miocene, and Eocene, the Greek diphthongs ei and 

 ai are changed into the vowels i and e, in conformity with the idiom of our lan- 

 guage. Thus we have Encenia, an inaugural ceremony, derived from iv and 

 KKIVOS, recens; and as examples of the conversion of ei into i, we have icosahedron. 



I have heen much indebted to my friend, the Rev. W. Whewell, for assisting 

 me in inventing and anglicizing these terms, and I sincerely wish that the numer- 

 ous foreign diphthongs, barbarous terminations, and Latin plurals, which have 

 been so plentifully introduced of late years into our scientific language, had been 

 avoided as successfully as they are by French Naturalists, and as they were by the 

 earlier English writers, when our language was more flexible than it is now. But 

 while I commend the French for accommodating foreign terms to the structure of 

 their own language, I must confess that no naturalists have been more unscholar- 

 like in their mode of fabricating Greek derivatives and compounds, many of the 

 latter being a bastard offspring of Greek and Latin. 



