vii] WATER-SPIDERS 47 



CHAPTER VII 



WATER-SPIDERS 



HERE is the place to insert a short account of some 

 near relations of Agelena which we shall certainly 

 not meet in our walk, but of which the mode of life is 

 too interesting to be altogether passed over in silence. 



We have seen that the class Crustacea (crabs, 

 shrimps etc.) is the great division of the Arthropoda 

 entirely adapted to an aquatic life, breathing, by 

 means of gills, the air which is dissolved in the water. 

 Insects and spiders are air-breathing, and properly 

 belong to the land ; yet there are many insects which 

 pass their early stages often the greater portion of 

 their life in the water, and some which are very 

 fairly at home there when adult. Such insects often 

 have gills when young, and are therefore at that 

 period true water animals, like the Crustacea. 



The Arachnida that division of the Arthropoda 

 to which the spiders belong include a few groups 

 which permanently inhabit the sea, and could not 

 live on land. There are even some weird creatures 

 called Sea-spiders (Pycnogonids), but these do not 

 concern us, for they are very far removed from the 

 true spiders which are the subject of our investi- 

 gations. 



