ANNULOSA: ARACHNIDA. 



317 



In the Spiders (fig. 162, 4) each falx or mandible terminates 

 in a sharp movable hook, which possesses an aperture at its 

 extremity communicating by a canal with a gland, which is 

 placed in the preceding joint of the mandible, and secretes a 

 poisonous fluid. The maxillary palps in the Spiders are long, 

 jointed appendages, terminated in the females by pointed claws, 

 but frequently swollen, and carrying a special sexual apparatus 

 in the males. 



In the Scorpions (fig. 162, i) the mandibles are short and 

 terminate in strong pincers, or " chelicerse." The maxillary 



^ \4 



Fig. 162. Morphology of Arachnida, i. Organs of the mouth in the Scorpion, on 

 one side : m Mandibles (antennae) converted into chelae, and called the chelicerae ; 

 / Maxillary palpi greatly developed, and forming strong chelae. 2. Telson of the 

 Scorpion. 3. One of the abdominal segments of the Scorpion, showing the "stig- 

 mata," or apertures of the pulmonary sacs. 4. Tegenaria chrilis, the common 

 Spider (male), viewed from below: ^ Spinnerets ; tn Mandibles with their perforated 

 hooks below the mandibles are the maxillae, and between the bases of these is the 

 , labium ; p The maxillary palpi with their enlarged tumid extremities. 



palpi are also greatly developed, and constitute powerful grasp- 

 ing claws, or " chelae." In the genus Galeodes, the mandibles, 

 like those of the Scorpion, constitute " chelicerae," though com- 

 paratively much larger and longer ; but the maxillary palps are 

 not developed into " chelae." 



With regard to antennae, these organs, as such, do not exist 

 in the Arachnida. It is generally believed, however, that the 

 mandibles of the Arachnida are truly homologues, not of the 

 parts which bear the same name in the other Arthropoda, but of 

 \heantennce; and the name of " falces " is thus best applied to 

 them. The antennae, therefore, of the Spiders are converted 



