3196 THE JOINTED ANIMALS 



Desis, found on the coasts and coral reefs of the South- African, Indo- Malayan, and 

 Australian seas. At low water the reefs and rocks upon which they live are un- 

 covered; but at the rising of the tide the spiders retreat into holes and crannies, 

 where they surround themselves with a layer of silk strong enough to keep out 

 water. They are good swimmers and feed upon small fish, crustaceans, etc. The 

 Argyronetidce live in fresh water, and are represented only by the water spider 

 (Argyroneta aquatica), frequenting ponds and ditches in the British Islands and 

 other parts of Europe. Among the waterweeds the water spider spins a thimble or 

 bell-shaped web, the aperture of which opens downward. Then, ascending to the 

 surface and thrusting its abdomen out of the water, it succeeds, by some process 

 not clearly understood, in enveloping the hinder part of its body in a film or bubble 

 of air. Retaining this bubble in position by means of its hinder pair of legs, the 

 spider swims down to its web, and inserting its abdomen into the aperture of the 

 bell, sets free the bubble of air, which rises to the upper part of the cavity of 

 the web and replaces a certain quantity of water. The spider then fetches down 

 another bubble, and repeats the process until the web is filled with air; it then has 

 a water-tight chamber, in which it can dwell till all the oxygen is consumed. Here 

 the eggs are laid and hatched. This spider lives on insects which it catches in the 

 water. Belonging to the family Agalenidce is the genus Agalena, of which a British 

 species {A. labyrinthica) is abundant in most districts, and spins a large sheet-like 

 web upon hedges and bushes. At its inner extremity the web ends in a tube com- 

 municating at the back with the bush, into which the spider makes its escape when 

 pursued. This spider is exceedingly agile, running with great speed either on the 

 ground or the upper side of its web. It has an ingenious method of overcoming in- 

 sects like bees, with which it is afraid to come to close quarters, when they have 

 fallen into the web. Attaching a thread to a spot close at hand, the spider runs in 

 circles round and round its entangled prey, letting out the thread as it goes and 

 gradually enveloping the insect, and effectually putting a stop to all struggles. 

 Then, when it is tightly bound, the spider cautiously approaches, and, inflicting a 

 bite upon the insect, puts an end to its life. Also belonging to this family is the so- 

 called cardinal spider {Tegenaria guyonit), erroneously believed peculiar to the 

 chapel at Hampton Court. Although none of the families of Tubitelarice hitherto 

 considered possess the cribellum and calamistrum, one family {Amaurobiidce) is 

 supplied with these organs. A well-known form is Amaurobius similis, which lives 

 in holes in walls and ivy, where it spins an irregular, untidy, woolly web. The 

 Plagitelarice contain the family Pholddce, of which the genus Pholcus is the best 

 known; one species (P. phalangioides} being not uncommon in the south of Eng- 

 land, where in sheds and outhouses it spins a characteristic web, composed of a 

 tangled mass of irregularly interlacing threads. This species has exceedingly long 

 and slender legs, which at first sight give it a close resemblance to the harvest 

 spiders. It moves slowly and clumsily; but when alarmed has a habit of hanging 

 downward in the web, by the tips of the toes, and swinging the body round and 

 round with such rapidity that it becomes almost invisible. No nest is made, and 

 the cocoon consists of a flimsy network, enveloping the eggs, which the mother 

 carries about in her mandibles. 



