68 ORIGINATION OF LIVING BEINGS. 



record ; there are some who imagine that the earliest 

 forms of life of which we have as yet discovered any 

 records, are in truth the forms in which animal life be- 

 gan upon the globe. The grounds on which they base 

 that supposition are these : — That if you go through 

 the enormous thickness of the earth's crust and get 

 down to the older rocks, the higher vertebrate animals 

 — the quadrupeds, birds, and fishes — cease to be found ; 

 beneath them you find only the invertebrate animals ; 

 and in the deepest and lowest rocks those remains be- 

 come scantier and scantier, not in any very gradual 

 progression, however, until, at length, in what are sup- 

 posed to be the oldest rocks, the animal remains which 

 are found are almost always confined to four forms, — 

 Old/ia?nia, whose precise nature is not known, whether 

 plant or animal ; Lingula, a kind of mollusc ; Trilo- 

 bites, a crustacean animal, having the same essential 

 plan of construction, though differing in many details 

 from a lobster or crab ; and Hymenocaris, which is 

 also a crustacean. So that you have all the Fauna re- 

 duced, at this period, to four forms : one a kind of ani- 

 mal or plant that we know nothing about, and three 

 undoubted animals — two crustaceans and one mollusc. 

 I think, considering the organization of these mol- 

 lusca and Crustacea, and looking at their very complex 

 nature, that it does indeed require a very strong ima- 

 gination to conceive that these were the first created of 

 all living things. And you must take into considera- 

 tion the fact that we have not the slightest proof that 

 these which we call the oldest beds are really so : I re- 

 peat, we have not the slightest proof of it. When you 

 find in some places that in an enormous thickness of 

 rocks there are but very scanty traces of life, or abso- 



