

198 gfog S*rm0ns, (Stesags, mtb Jjkbiefas," [ix. 



Thus the chalk contains remains of those strange 

 flying and swimming reptiles, the pterodactyl, the ich- 

 thyosaurus, and the plesiosaurus, which are found in no 

 later deposits, but abounded in preceding ages. The 

 chambered shells called ammonites and belemnites, 

 which are so characteristic of the period preceding the 

 cretaceous, in like manner die with it. 



But, amongst these fading remainders of a previous 

 state of things, are some very modern forms of life, 

 looking like Yankee pedlars among a tribe of Eed 

 Indians. Crocodiles of modern type appear ; bony 

 fishes, many of them very similar to existing species, 

 v, almost supplant the forms of fish which predominate 

 in more ancient seas ; and many kinds of living shell- 

 fish first become known to us in the chalk. The vege- 

 tation acquires a modern aspect. A few living animals 

 are not even distinguishable as species, from those which 

 existed at that remote epoch. The Globigerina of the 

 present day, for example, is not different specifically 

 from that of the chalk; and the same may be said 

 of many other Foraminifera. I think it probable that 

 critical and unprejudiced examination will show that 

 more than ohe species of much higher animals have had 

 a similar longevity ; but the only example which I can 

 at present give confidently is the snake's-head lamp- 

 shell (Terebrfttulina caput serpentis), which lives in 

 our English seas and abounded (as Terebratulina striata 

 d/authors) in the chalk. 



"""TireHxragest line of human ancestry must hide its 

 diminished head before the pedigree of this insignificant 

 shell-fish. We Englishmen are proud to have an ancestor 

 who was present at the Battle of Hastings. The an- 

 j^ cestors of Terebratulina caput serpentis may have been 

 present at a battle of Ichthyosauria in that part of the 

 sea which, when the chalk was forming, flowed over the 



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