392 CLASS ARACHNIDA. 



struggle with it, the spider retires for a moment, to wait until 

 the other has lost its strength, or become more entangled. 

 But if there is nothing to fear, the spider hastens to fetter its 

 prey, by winding its threads of silk round its body, which 

 sometimes completely envelope it, and form a covering that 

 withdraws it from our sight. 



Lister has asserted, that the spiders ejaculate and dart out 

 their threads, in the same manner as the porcupines shoot 

 their quills, wdth this difference, that the latter weapons, 

 according to the popular opinion, are detached from the body, 

 while in the spiders, these threads, though pushed to a dis- 

 tance, remain attached to the animal. This feat has been 

 considered impossible. Nevertheless, we have seen threads 

 issuing from the nipples of some thomisi, directed in a right 

 line, and forming, as it were, moveable radii, when the animal 

 moved circularly. Another use of the silk, and common to all 

 the female araneides,isin the construction of cocoons, destined 

 to enclose their eggs. The contexture and the form of these 

 cocoons are variously modified, according to the habits of 

 the races : they are generally spheroidical. Some have the 

 form of a cap, or that of a kettle ; some are supported on a 

 pedicle or stem, or terminate in a knob. Foreign substances, 

 such as earth, leaves, &c. sometimes cover them, at least 

 partially. A finer tissue, a sort of wadding, or down, often 

 envelopes the eggs internally : they are either free or agglu- 

 tinated, and more or less numerous. These animals, being- 

 very voracious, the males, to avoid all surprise, and not to be 

 the victims of a premature desire, approach their females at 

 the season of love with the most extreme distrust and the 

 greatest circumspection. The apparatus of generation in the 

 males, or at all events that which is presumed to be so, is 

 usually very complicated and various, formed of scaly pieces, 

 more or less hooked and irregular, and of a white fleshy body, 

 on which vessels are sometimes perceived, of a sanguine 



