Y8 [Assembly 



mous i)ed of White chalk is made up of the skeletons or shells 

 of minute living things ordinarily spoken of as animalcules, so 

 small that they are not to be detected without the aid of the 

 microscope. The oldest now living forms of earth belong to these 

 tiny beings, for it is believed that some of those found fossil in 

 the Chalk are identical with some which live in the ocean to-day. 

 Every shell, every fish or other relic found in the Cretaceous 

 strata, is of an extinct species ; of many, no analogous or closely 

 similar form now exists, but these minute organisms still survive 

 without change. 



The lower beds of rock which overlie the Cretaceous system, 

 called the Tertiary formations, exhibit in their fossils a close 

 resemblance to now-existing forms, and some of them are the 

 same. As we examine the fossils of higher and higher strata of 

 the Tertiary, we find the proportion of extinct species gradually 

 diminishing, and that of still extant species increasing, until in 

 the Upper Tertiary they show a set of animal inhabitants and 

 plants almost precisely the same with those which now exist ; 

 the same trees, the same quadrupeds, the same shells buried in 

 the newest tertiary strata being still found living. Thus, through 

 the enormous succession of strata which we have traced, we have 

 found a gradual advance in their fossil relics : the first shells 

 beginning in the Lower Silurian, or Potsdam sandstone ; the first 

 fishes, in the Lower Devonian, or Oriskany sandstone ; the first 

 land-plants, in the Middle Devonian, or Hamilton group ; the 

 first reptiles, in the Carboniferous ; the first birds, in the Triassic, 

 or New K-ed sandstone ; the first warm-blooded quadrupeds, in 

 the Jurassic ; while the more modern mammalia, the ox, horse, 

 deer, the canine and feline tribes and others now abundant, as 

 well as the modern trees, such as oaks, beeches, maples, palms, 

 etc., first appear in the Tertiary. 



The remains of Man and his works are found only in the 

 newest of all the Tertiary beds, which appear to have an age of 

 not many thousand years. Man thus appears to be the latest 

 introduced on earth of all its living tenants, or at least to have 

 appeared only among the latest creations. The earliest relics of 

 him appear to be some rude knives and arrow-heads of flint, — 

 such as are universal among savage hunter-tribes ;— which have 

 been found in association with bones of extinct animals, buried 

 in gravel beds in France and England. There is yet some doubt 

 and uncertainty hanging about these evidences of human anti- 



