ANNULOSA : ARACHNIDA. 22Q 



sacs is smaller in the true Spiders than in the Scorpions, being 

 either two or four, opening by as many stigmata upon the under 

 surface of the abdomen. 



The head bears from six to eight simple eyes ; the mandibles 

 are simply hooked, and are perforated by the duct of a gland 

 which secretes a poisonous fluid ; and the maxillary palpi are 

 never chelate. 



Spiders (fig. 77) are all predaceous animals, and many of 

 them possess the power of constructing webs for the capture 

 of their prey or for lining their abodes. For the production of 

 the web, Spiders are furnished with special glands, situated at 

 the extremity of the abdomen. The secretion of these glands 

 is a viscid fluid which hardens rapidly on exposure to air, and 

 which is cast into its proper, thread-like shape, by being passed 

 through what are called the "spinnerets." These are little 

 conical or cylindrical organs four or six in number, situated 



Fig- 77- Araneida. Theridion riparium (female). 



below the extremity of the abdomen. The excretory ducts of 

 the glands open into the spinnerets, each of w r hich has its 

 apex perforated by a great number of minute tubes, through 

 which the secretion of the glands has to pass before reaching 

 the air. Many spiders, however, do not construct any web, 

 unless it be for their own habitations, but hunt their prey for 

 themselves. 



As regards the reproductive process in the Spiders, it 

 appears certain that the act of copulation, so to speak, is per- 

 formed by the males by means of the maxillary palpi, the 

 extremities of which are specially modified for this purpose. 

 The testes are abdominal, but the semen appears to be stored 

 up in the enlarged extremities of the maxillary palps, which 

 thus perform the part of the vesiculse seminales. " The most 

 careful observations, repeated by the most attentive and expe- 

 rienced entomologists, have led to the conviction that the ova 



