304 THE SEA SHORE 



passes through all its stages within reach of the waves. Another 

 of the Brachetytra (Bledius) burrows into the sand or mud near 

 high-water mark, throwing up the debris as it proceeds. Both 

 these beetles are carnivorous, and the latter is in turn preyed upon 

 by a ground beetle of the genus Dyschirius, which hunts and 

 devours it within its own home. 



The reader will have observed that the sub-kingdom Arthropoda 

 is not only a very extensive one in the sense that it contains a vast 

 number of animal forms, but also that its members exhibit a very 

 great variety of form and structure ; and the beginner will probably 

 find no little difficulty in locating his specimens in their correct 

 position in the scale of life. The following table, however, will 

 serve to show the general classification of the group at a glance, 

 and thus form a basis for a more detailed study at any future 

 tune: 



SUB-KINGDOM ARTHROPODA 



CLASSIFICATION 



Class CRUSTACEA. 



Sub-class ENTOMOSTKACA. 



Order Astracoda Free. Body enclosed in a bivalve shell. 

 Order Copepoda Free. Five pairs of feet adapted for swimming. 

 Order Cirripedia Sessile. Enclosed in a shell of many valves. 

 Order Branchiopoda Free. Gills attached to feet. 

 Sub-class MALACOSTBACA. 



Division EDKIOPHTHALMATA, or Sessile-eyed Crustaceans. 

 Order Isopoda Body flattened. Seven pairs of legs equal. 

 Order Amphipoda Body flattened laterally. Legs adapted for 



both walking and swimming. 

 Division PODOPHTHALMATA, or Stalk-eyed Crustaceans. 



Order Stomapoda Anterior appendages directed towards the 



mouth. 



Order Schizopoda Cleft-footed Crustaceans. 

 Order Decapoda Ten-footed Crustaceans. 

 Sub-order Macrura Great-tailed. Lobsters, &c. 

 Sub-order Brachyura Short-tailed. Crabs. 

 Class ARACHNOIDEA. 



Order Scorpionidse Scorpions. 

 Order Araneidse Spiders. 

 Order Acarina Mites. 



