594 HISTORICAL GEOLOGY. 



bable on p. 147), the beginning of the series is even below the types 

 of Mollusks and Trilobites. (2.) Fishes preceded Reptiles; Rep- 

 tiles, Mammals; brute Mammals, Man. (3.) Articulates commence 

 with the inferior marine species, Worms and Crustaceans ; they rise 

 in the Carboniferous age to Insects, the superior class ; and later to 

 the highest Insects, the Hymenopters (the tribe containing the 

 Bee). (4.) Crustaceans are first represented by Entomostracans, as 

 Trilobites ; then by the Shrimp and Lobster tribes, in the Carboni- 

 ferous and Reptilian ages ; then true Crabs, in the later Reptilian 

 and Mammalian ages ; and finally the highest division of Crabs 

 (the Maioid. or Triangular), in the age of Man. 



2. A type not instituted usually by the introduction of its lowest species, or 

 developed by the appearance of species in the order of grade. — (1.) Snakes, 

 while inferior to Turtles, Saurians, and Lacertians, are not known 

 as fossils until the Tertiary. (2.) Edentates are not known until 

 after the Pachyderms and Carnivores of the early Tertiary. (3.) 

 Mosses and Lichens appear long after the great Acrogens of the 

 Carboniferous Age. (4.) Ganoids and Selachians are not the lowest 

 of fishes in rank. (5.) Trilobites of the oldest Silurian are not the 

 lowest of Crustaceans. Barnacles rank much below them, and yet 

 are not known until the middle of the Reptilian age. 



The grand series taken as a whole was an ascending one, but 

 not by lineal ascent from the lowest to the highest. 



3. The culmination of the various groups of species, or their time of greatest 

 expansion, not confined to any one period in geological history ; but each group 

 having its own special time, some passing it in the Palaeozoic, others in the 

 Mesozoic or Cenozoic, and others not having reached it before the age of Man. 

 — Numerous examples of this general truth are presented in the 

 tables on pp. 400 and 572, and special examples are also mentioned 

 on pp. 399 and 496. 



The culmination of a type is marked in the culmination or great- 

 est expansion of the highest group under the type, and not by that 

 of all the groups which constitute it. See p. 496 for examples. 



The Vegetable and Animal kingdoms have now their periods of culmination. 

 But, excluding Man, the Animal kingdom passed its climax in the Post-tertiary, 

 when the Carnivores and Herbivores were largest and most numerous. 



Under the Animal kingdom, the sub-kingdom of Mollusks culminated in the 

 later Mesozoic, when Cephalopods, the highest group, passed their climax ; that 

 of Articulates, in the present era, when Insects are most diversified and most 

 abundantly represented in the higher groups; that of Vertebrates, exclusive of 

 Man, in the Post-tertiary, the period being the same as for the Animal kingdom 

 as a whole, since it is the highest of the subdivisions. 



Under Articulates, Insects, Spiders, and also Crustaceans, have their culmina^ 

 tion in the present era. 



