402 ARACHNIDA, MYEIAPODA, AND INSECTA. 



the length of the body. Another Carboniferous genus is 

 Mazonia, which has been founded for the reception of an 

 Arachnide of uncertain affinities, but in some respects inter- 

 mediate between the Scorpionidce and the Pseudoscorpionida?, 

 from the Coal-measures of Illinois. Lastly, the Microlabis 

 of the Coal is believed to be most nearly allied to the 

 Pseudoscorpions. 



OEDER ARANEIDA. This order includes the true Spiders, 

 which are characterised by the amalgamation of the head 

 and thorax into a single mass, to which the generally soft 

 and unsegmented abdomen is attached ~by a constricted portion 

 or peduncle. Eespiration is effected by pulmonary sacs in 

 combination with air-tubes (tracheae). The head bears from 

 two to eight simple eyes. 



The oldest known Spiders occur in the Carboniferous 

 rocks. In the Coal - measures of Upper Silesia, Eoemer 

 has described a Spider, which is allied to the living Lycosa, 

 and which he has termed Protolycosa anthracophila. An- 

 other true Spider is the Palaranea borassifolia of the Coal- 

 measures of Bohemia (Fric). Other fossil Spiders have 

 been described from the Lithographic Slates of Solenhofen 

 (Middle Oolite), and from the Tertiary rocks, and a good 

 many species occur preserved in amber. 

 



CLASS MYRIAPODA. 



The Myriapods are Articulate animals in which the head 

 is distinct, and the remainder of the ~body is divided into 

 nearly similar segments. There is no marked boundary -line 

 between the thorax and abdomen, and the segments of the 

 latter carry locomotive limbs. There is one pair of jointed 

 antenna?, and the number of legs is always more than eight 

 pairs. ^Respiration is effected by air-tubes (trachece). 



The living Myriapods are divided into the four orders 

 Chilopoda, Chilognatha, Pauropoda, and Onychophora. In 

 the Chilopoda are the Centipedes, characterised by their 

 masticatory mouth and carnivorous habits, by the posses- 

 sion of legs in single pairs (usually from fifteen to forty 

 pairs), and by having antennae of from fourteen to forty or 



