186 LIFE, IN ITS INTERMEDIATE FORMS. 



Pulmonaria ; the Harvest-men and Mites to the latter, 

 and are called Trachearia. 



We naturally associate Spiders with cobwebs, and the 

 faculty of spinning threads from the hind part of the body 

 is one of their most marked characteristics ; but all do 

 not make webs, properly so called. In the south of Europe 

 and in the West Indies, certain large Spiders belonging to 

 the genus Cteniza are called Trap-door Spiders, from their 

 singular architectural instincts. The female excavates a 

 burrow in soft earth, an inch in diameter, and six to ten 

 inches in depth ; this is lined with a dense tapestry re- 

 * sembling paper, formed of her silk; and the mouth is 

 closed with a circular door, formed of many layers of silk, 

 with pellets of earth interwoven into the exterior, but 

 which is so smooth on the interior, and so accurately 

 formed, as to fit the orifice with the utmost accuracy ; 

 while a hinge of silk at one part of the circumference 

 allows the lid to be raised for the exit of the owner, when 

 it closes by its own elasticity. 



Judging from specimens which we have examined in 

 Jamaica, the lid is always punctured with a number of 

 holes, such as might be made by a very fine needle, which 

 penetrate through the whole substance, the light being 

 clearly seen through each hole. We have conjectured 

 that the object of these orifices may be the admission of 

 air and light into the cell, when the lid is tightly closed, 

 for the comfort of the inmate. The Spider habitually 

 resides in her well-built house, coming abroad to hunt, 

 and retreating with her prey to the bottom of her domain. 



In the hot parts of the world, Spiders (Mygale) closely 

 allied to these are found, which are often of immense size. 



