

THEIR GEOLOGICAL AGE. 205 



worthy research to English geologists and collectors, who 

 have access to local museums, in which the remains of the 

 Essex fluviatile deposits are preserved. (See page 251, note 1.) 



It has been objected to me by naturalist friends of emi- 

 nence, and for whose opinions I entertain the highest respect, 

 that there is a prima facie improbability that so many 

 Proboscidean species should have co-existed in the same 

 Pliocene fauna, namely, two Mastodons and three Elephants. 

 My reply is : First, go and examine the evidence in the 

 Astesan, where abundant remains of three of the species 

 occur within a limited area in the same alluvium, mixed up 

 with the same freshwater shells ; then examine the exten- 

 sion of the same deposits near Piacenza and Verona ; then 

 the deposits of the Val d'Arno ; and compare the association 

 of mammals in each. Secondly, the Miocene fossil fauna of 

 the Sewalik hills (exclusive of Ava and of the Nerbudda 

 Pliocene beds) presents a parallel case, where at least six 

 fossil species of Proboscideans are met with in beds of the 

 same age, in the same matrix, the same mineral condition, 

 and with the same associates ; namely, two Mastodons, 

 Tetraloph. latidens and Tetraloph. Sivalensis ; two Stegodons, 

 Steg. bombifrons and Steg. insignis ; one Loxodon, Lox. plani- 

 frons ; and one Euelephas, Euel. Hysudricus. Of five of these 

 forms, crania exist in the British Museum, besides the de- 

 tails of their dentition ; and the evidence of their distinct- 

 ness, founded on these crania, is quite as conclusive as that 

 upon which palaeontologists would distinguish the existing 

 Elephant from the Mastodon of North America, by the form 

 of their skulls. 



Prom the consideration of the various facts which I have 

 passed under review, I have been led to the conclusion that 

 the same mammalian fauna ranged throughout, from the 

 Crag up to the Thames Valley fluviatile deposits, and that 

 any division of them into older and newer Pliocenes, as 

 Pleistocenes and Post-Pliocenes, is untenable. It would seem 

 to me that in all the investigations where the classification of 

 the newer Tertiaries is concerned, too much stress has been 

 laid on the shell-evidence, while that which may be derived 

 from the mammalia has been in a great measure either over- 

 looked or undervalued. Like the artificial arrangement of 

 Linnaeus in plants, the shell-evidence has furnished a ready 

 and convenient means of arranging the strata conventionally 

 in successive order, regarded from one aspect; but it can 

 never satisfy the requirements of a natural philosophical 

 system, where the solution of the conditions of the higher 

 forms of terrestrial life constitutes the most important part 

 of the problem. The evidence must be taken from every side, 



