WOLF- AND TRAP-DOOB SPIDERS. 213 



The Vagrant or Wolf Spider. This insect catches its 

 prey by stealthily stalking it until within distance near 

 enough to admit of a sudden dart being successful in 

 effecting capture. Some species, before making the final 

 dart (e.g. Salticus scenicus'), fix a line of web upon the 

 surface over which they are creeping, so that whether their 

 station is vertical or horizontal with reference to the prey, 

 they can leap fearlessly, the thread in any case preventing 

 their fall. Dr. H. F. Hutchinson says that he has seen 

 this spider crawling over a looking-glass stalking its own 

 reflection. 1 



The following is quoted from Biichner : 



Less idyllic than the water-spider is our native hunting- 

 spider (Dolomedes Jimbriata), which belongs to those species 

 which spin no web, but hunt their victims like animals of prey. 

 As the Argyroneta is the discoverer of the diving-bell, so may 

 this be regarded as the discoverer or first builder of a floating 

 raft. It is not content with hunting insects on land, but 

 follows them on the water, on the surface of which it runs 

 about with ease. It, however, needs a place to rest on, and 

 makes it by rolling together dry leaves and such like bodies, 

 binding them into a firm whole with its silken threads. On 

 this raft-like vessel it floats at the mercy of wind and waves ; 

 and if an unlucky water-insect comes for an instant to the sur- 

 face of ~ the water to breathe, the spider darts at it with light- 

 ning speed, and carries it back to its raft to devour at its ease. 

 Thus everywhere in nature are battle, craft, and ingenuity, all 

 following the merciless law of egoism, in order to maintain 

 their own lives and to destroy those of others ! 



Trap-door Spiders. These display the curious in- 

 stinct of providing their nests with trap-doors. The nest 

 consists of a tube excavated in the earth to the depth of 

 half a foot or more. In all save one species the tube is 

 unbranched ; it is always lined with silk, which is con- 

 tinuous with the lining of the trap-door or doors, of which 

 it forms the hinge. In the species which constructs a 

 branching tube, the branch is always single, more or less 

 straight, takes origin at a point situated a few inches from 

 the orifice of the main tube, is directed upwards at an acute 



1 Nature, vol. xx., p. 581. 2 Loc. tit., p. 323. 



