54 SPIDERS [CH. 



action and superior strength. But other crab-spiders 

 lead a less strenuous life; their habit is to lurk in 

 moss, lichen, or flowers till an insect draws near enough 

 to be seized without any great expenditure of energy. 

 Now in the case of some of these spiders the 

 chance of obtaining a meal is very greatly increased 

 by a remarkable similarity of coloration between the 

 spider and its usual hunting ground. The spider's 

 object is to remain invisible, and concealment is 

 obviously more easy if its colour matches that of its 

 environment. To a greater or less extent this 

 protective coloration as it is called prevails uni- 

 versally: spiders are seldom conspicuous objects 

 among their usual surroundings, but it is only 

 occasionally that we meet with cases of very 

 remarkable colour adaptation. Two such, however, 

 occur among English crab-spiders. One is a species 

 not uncommon in the south of England, and fairly 

 plentiful in the Xew Forest, where it is to be sought 

 among the lichen on the tree trunks, where its blue- 

 grey body, marked with black and white blotches 

 makes it practically invisible except when in motion. 

 It rejoices in the name of Philodromm margaritatus. 

 The other case is that of the spider known as 

 Misumena vatia, which is variable in colour, some 

 specimens being yellow and others pink, while a 

 variety of the species has a blood-red streak 

 decorating the front part of its abdomen. If it were 



