THE CARBONIFEROUS PERIOD. 



181 



Decapods (Brachyura), in which the abdomen is short, not 

 terminated by a tail-fin, and tucked away out of sight beneath 

 the body, is at present not known to be represented at all in 

 the Carboniferous deposits. 



In addition to the water-inhabiting group of the Crustaceans, 

 we find the articulate animals to be represented by members 

 belonging to the air-breathing classes of the Arachnida, Myria- 

 poda, and Insecta. The remains of these, as might have been 

 expected, are not known to occur in the marine limestones of 

 the Carboniferous series, but are exclusively found in beds asso- 

 ciated with the Coal, which have been deposited in lagoons, 

 estuaries, or marshes, in the immediate vicinity of the land, and 

 which actually represent an old land-surface. The Arachnids 

 are at present the oldest known of their class, and are repre- 

 sented both by true Spiders and Scorpions. Remains of the 

 latter (fig. 123) have been found both in the Old and New 



Fig. 123. Cycloplithali) 



~ senior. A fossil Scorpion from the Coal-measures 

 of Bohemia. 



Worlds, and indicate the existence in the Carboniferous period 

 of Scorpions differing but very little from existing forms. The 

 group of the Myriapoda, including the recent Centipedes and 

 Galley-worms, is likewise represented in the Carboniferous strata, 



