ities encounter each other in the centre. Then conceive these knives to have the edges of their blades serrated with a row of fine teeth commencing near the haft, and on the handle itself five large, pointed teeth, shaped like the head of a lance, and upon which the saw-like blade can be brought to work to and fro." The large claw or horn (Fig. 3) answers to the blade, a representing its fine teeth, while b shows the five lance-like teeth in the handle against which the blade works. But, besides these mandibles, the spider possesses a smaller pair of jaws, called
Fig. 3.
Termination of the Jaw, or Mandible.—a, Row of Teeth on the Claw; b, Basal Joint of Mandible, showing the Five Large Teeth; c, Commencement of Poison-sac; d, Course of the Poison-duct. The last two are only visible when the mandible has been carefully bleached with chlorine.
the "maxillæ," which also have finely-toothed edges like deeply-cut rasps that most probably operate one against the other, to enlarge the wound made by the mandibles. This looks formidable enough, but it is not the worst. Nature has equipped the spider for very thorough work. This combination of dirks and saws is poisoned. At the basal joints of the mandibles there is a receptacle filled with a subtle venom which is conveyed through a tube (Fig. 3, d) to the pointed extremity of the blade. The moment this pierces the body of the prey, the poison is emitted, and, entering the wound, renders it fatal, probably at the same time benumbing the sensibility of the victim. The injected poison is nearly colorless, and possesses most of the properties that exist in the venom of the rattlesnake or the viper. The bite of a large spider on the back of the hand has been known to swell the whole arm, so that it was hardly recognizable as belonging to the human figure.
There is a famous spider called the tarantula, from the town of Tarentum, in Italy, where it is plentiful. It is believed by the people of that region that the bite of the tarantula produces the most ex-
