Elementary text-book of zoology, tr Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 403 Order 3.—ARAXEIDA * ^SPIDERS). Arachnida with poison glands in the subchelate chelicerce; with pediform pedipalpi and stalked unsegmented abdomen. They have four or six spinning mcynmillce, and two or four pulmonary sacs. The peculiar shape of the true spiders is due to the swollen and unsegmented abdomen, the base of which is constricted to form the stalk by which it is united to the rest of the body (fig. 392). T
Elementary text-book of zoology, tr Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 403 Order 3.—ARAXEIDA * ^SPIDERS). Arachnida with poison glands in the subchelate chelicerce; with pediform pedipalpi and stalked unsegmented abdomen. They have four or six spinning mcynmillce, and two or four pulmonary sacs. The peculiar shape of the true spiders is due to the swollen and unsegmented abdomen, the base of which is constricted to form the stalk by which it is united to the rest of the body (fig. 392). The large subchelate chelicene, which project beyond the front of the head, consist of a powerful basal portion grooved on the inner side, and a claw-shaped terminal joint at the point of which the duct of a poison gland opens (fig. 393). At the moment of the bite the secre- tion of this gland flows into the wound, and in the case of small animals causes an almost instanta- neous death. The pedipalpus bears on its broad coxal joint, which constitutes a kind of biting- blade (fig. 392 K), a many- jointed palp, the terminal re- gion of which is peculiarly modified in the male and func- tions as a copulatory organ. The mouth is bounded on the under side by an unpaired J FIG. 393.—Poison gland plate, forming a sort of lower and terminal joint of lip. The four pairs of usually long legs, whose form and size FIG. 392.—Dyidera ery- vary according to the manner «n»a from the ventral of Jife end with two toothed side (regne animal). -2y,cheiicera:.o,pedi. claws, to which a small claw (Tk) and several paipus; r, basal joint accessOry claws may be added (fig. 394). The (jaw) of pedipalpus; » * p, lungs; Sf, stigma of abdomen in the female is always larger and more
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