MASON SPIDERS. 65 



form one of the principal subdivisions of this family, have four 

 pulmonary sacs. Some of them are of large size, and are known, 

 in South America, among the French, under the name of crab- 

 spiders ; there is one, which, with the legs extended, covers a 

 circular space of seven inches in diameter. They live on trees 

 or among rocks. Other Mygales, much smaller, however, in- 

 habit the South of France, and dig subterranean galleries in form 

 of tubes, in dry and mountainous situations, the apertures to 

 which are furnished with movable doors. 



'* The mason spiders (Mygale coementaria) excavate for themselves sub- 

 terranean caverns, in which these marauders lurk, secure from detection, 

 even by the most watchful foe : nor could any robber's den, which ever 

 existed in the wild regions of romance, boast more sure concealment from 

 pursuit, or immunity from observation. The construction of these singular 

 abodes has long excited the admiration of the naturalist: a deep pit is first 

 dug by the spider, often to the depth of one or two feet, which, being care- 

 fully lined throughout with silken tapestry, affords a warm and ample 

 lodging ; the entrance to this excavation is carefully guarded by a lid or 

 door, which moves upon a hinge, and accurately closes the mouth of the 

 pit. In order to form the door in question, the Mygale first spins a web 

 which exactly covers the mouth of the hole, but which is attached to the 

 margin of the aperture by one point only of its circumference, this point 

 of course forming the hinge. The spider then proceeds to lay upon the 

 web a thin layer of soil collected in the neighbourhood of her dwelling, 

 which slve fastens with another layer of silk ; layer after layer is thus laid 

 on, until at length the door acquires sufficient strength and thickness : 

 when perfected, the concealment afforded is complete; for, as the outer 

 layer of the lid is formed of earth precisely similar to that which surrounds 

 the hole, the strictest search will scarcely reveal to the most practised eye 

 the retreat so singularly defended." 7'. Rymtr Jones. 



The other Aranei'dne never have more than two pulmonary 

 sacs : a large number is known ; they are subdivided into many 

 tribes, which, in turn, are composed of many genera. 



23. The Ardnece sedentdrice, or sedentary spiders, form one 

 of these divisions. They are remarkable for their habit of 

 remaining in their webs, and keeping in their snares or close by 

 them, to surprise their prey, instead of going abroad in pursuit 

 of food. 



24. To this tribe belong the spiders, properly so called (Ardnea 

 or Tegena'ria^), which live in the interior of our houses, in hedges, 

 along the road-sides, &c., and weave a large, nearly horizontal 

 web, at the upper part of which is a tube where they keep them- 

 selves perfectly at rest. 



25. Other Aranei'dse are wandering, and constitute the tribe of 

 Vagabunda. They make no web, but watch for their prey ann 



23. How are sedentary spiders distinguished ? 



24. What are spiders, properly so called ? 



25. What is the taren'tula ? o * 



