8o6 THE POPULAR SCIENCE MONTHLY. 



structed, the mason stretches a little web over the opening, stick- 

 ing to it such particles of earth as it may find within its reach. 

 A new sheet of silk is stretched over this, and a second layer is 

 formed ; and the process is repeated till the trap-door has obtained 

 the requisite thickness. Then it shaves the edges to make the 

 contours even, and the door is finished. If we compare several 

 nests of the same species, we shall notice considerable differences 

 in the merit of the work, from the greatest excellence down to 

 comparative inferiority. Sometimes we find nests with two doors 

 and two vestibules. In the majority of instances of this kind, one 

 of the trap-doors has been condemned. Sometimes the hole is 

 provided with an ascending annex, not opening out upon the sur- 

 face but provided with an interior door separating a smaller 

 chamber from the main abode. This puts the spider to advantage 

 against an enemy that may have gained access to the main cham- 

 ber. The ctenizas take a variety of precautions against being 

 discovered. Sometimes the trap-doors are disguised by looking 

 in no way different from the ground around them. In other 

 places they are concealed by means of moss, lichen, grass-blades, 

 bits of straw, or whatever foreign bodies it may be convenient to 

 strew around and over them. The masons are very diligent in 

 their work. If one of them is deprived of his retreat, he will re- 

 place it in a night or two. But, notwithstanding their skill in 

 construction, the best observers affirm that young spiders will not 

 abandon a nest when it has become too narrow for them. They 

 have the art of enlarging them so that they shall alwa^^s be at 

 ease within. The Austrian naturalist, Erber, met in the island 

 of Tinos, in 1868, a previously unknown species. He studied 

 its habits and found that it came out of its nest every even- 

 ing to make an excursion, but left its door open, fastening it 

 back to some stone or plant-stalk, protecting the entrance by 

 weaving over it a net which it destroyed on its return in the 

 morning. 



The trap-door spiders have been seen in many parts of the 

 globe, but usually in countries where a high temperature prevails. 

 They are abundant in the countries around the Mediterranean, 

 and have been observed in the Austral lands and in America. A 

 species of very fair proportions, the Cteniza Californica, lives in 

 California. A living specimen was kept and observed by M. Hip- 

 polyte Lucas for four months in the Museum d'Histoire naturelle. 

 The observer succeeded in opening the door of the cell and pre- 

 senting the spider with a fly. The cteniza, hungry after a long 

 voyage, seized the fly at the entrance of its burrow, but retired to 

 the back upon the attempt being made to draw it out ; and it con- 

 tinued suspicious, even toward its friend. One night, after it had 

 had a few days of good feeding, it sealed the circumference of its 



