

MYRIAPODA OF NORTHWESTERN NORTH 



AMERICA 



BY 0. F. COOK 



THE four classes of Arthropoda formerly arranged under the 

 name Myriapoda are no longer believed to constitute a natural 

 group, the agile, carnivorous Chilopoda with one pair of legs 

 on each joint of the body having closer affinities with the true 

 insects than with the slow-moving Diplopoda or thousand-legged 

 ' worms.' The latter subsist on decaying vegetable matter and 

 have two pairs of legs on most of the body segments. Related 

 to the Diplopoda are two other classes of minute animals, the 

 Symphyla and Pauropoda, not yet discovered in Alaska. 



Class DIPLOPODA. 



The Diplopoda are a predominately tropical group, though with 

 numerous representatives in the temperate regions, some of which 

 have been reported from rather high latitudes in Scandinavia and also 

 in Siberia, but only three species have been reported from Alaska. 

 Unlike the Insects and Molluscs, the Diplopoda attract little popular 

 attention, and they are neither useful nor injurious to the extent of de- 

 manding investigation for economic reasons. They have, however, 

 a unique scientific value as probably affording a better foundation for 

 distributional studies than any other group. Owing to their retiring 

 habits, slow movements, lack of wings, and inability to withstand ex- 



(49) 



