8 OSBORN. 



Without question the final classification will be by a synthesis of 

 evidence derived from invertebrate and vertebrate remains, from 

 the comparison of marine, fresh water and terrestrial forms of 

 life with each other and with earth movements. In numerous 

 instances the exclusive use of one class of evidence has led to 

 serious errors. 



The great faunal Periods or Systemes, Eocene, Miocene, 

 Pliocene, and Pleistocene we owe to Lyell. The Oligocene 

 was proposed by Beyrich ('54, pp. 640-666), chiefly on geo- 

 logical grounds, and although confirmed by the Berlin Geolog- 

 ical Congress some doubts are entertained as to its ultimate 

 utility and survival. 



D'Orbigxy, divided the Eocene into the lower (/) S//cs- 

 sonicii, in which we find fossil mammals deposited chiefly north 

 of Paris around the Suessonien gulf, and the upper (//) Pirn'sii'u 

 in which the deposits are chiefly around Paris and in the Hel- 

 vetien canal of the south of France and Switzerland. 



The stages and substages of the palsearctic Tertiary em- 

 ployed in the TJiird Trial S/iect, are chiefly the proposals of 

 Mayer-Eymar ('89), d'Orbigny, Dumeril, Suess, and Lap- 

 parent ('85) — all invertebrate palaeontologists. The histoiy 

 or authorship and synonj'my of the Etagcs, Monticn, Thancticn, 

 Suessonien, etc., may be found in the two palaeogeographical 

 essays by Mayer-Eymar ('89, p. 26), and Canu ('95, pp. 

 53-56), in which a reclassification of the entire Tertiary is 

 advocated upon the hypothesis of the relation between the peri- 

 helions of the globe and the sedimentary substages, as shown in 

 the Tableau i, of Canu ('95, pp. 12-13). For the purposes 

 of the mammalian palaeontologist however, the Lyellian sys- 

 tem is more convenient. 



Valuable tables of European faunal parallels are given by 

 V. Zittel ('93). The fullest lists of European mammals in 

 different horizons are those collected by Schlosser ('87-'90) 

 and Deperet ('85-'95) in his memoirs on the Miocene and Pli- 

 ocene. A mine of wealth for an investigation of this kind is 

 Schlosser' s Literaturberieht {'^Z-^1) ; the writer has referred 

 to it constantly and can hardly express his indebtedness. 



