8 RELICS OF PRIMEVAL LIFE 



man himself, the familiar groups of Beasts, Birds, 

 Reptiles, and Fishes. The latter consists of the 

 great swarms of creatures included under the terms 

 Insects, Crustaceans, Worms, Cuttle-fishes, Snails, 

 Bivalve Mollusks, Star-fishes, Sea-urchins, Coral 

 Animals, Sea - jellies, Sponges, and Animalcules. 

 This mixed multitude of animals, mostly of low 

 grade and aquatic, includes a vast variety of forms, 

 which, though comparatively little known to ordinary 

 observers, are vastly numerous, of great interest to 

 naturalists, and, as we shall find, greatly older in 

 geological date than the higher animals. 



It will be seen by a glance at the diagram that 

 the higher vertebrates are of most recent origin, 

 man himself coming in as one of the newest of all. 

 Only the lower reptiles or batrachians and the 

 fishes extend very far back in geological time. 

 None of the other vertebrate groups reach, so far 

 as yet known, farther back than the middle of the 

 geological scale — probably in point of time very 

 much less than this. Those of the invertebrates 

 that breathe air reach no farther back than the 

 fishes, possibly not so far. On the other hand, all 



Metazoa and Protozoa^ seems more arbitrary and unequal, and 

 therefore of less practical value. 



