Elements of comparative zoology (1904) Elements of comparative zoology elementsofcompar1904king Year: 1904 232 SYSTEMATIC ZOOLOGY. These forms live in the sea, feeding on worms, etc., found in the sea-bottom, coming to the shore in spring and early summer to lay their eggs. The horseshoe crabs are without any economic importance, as they are useless as food, but they are extremely interesting to the naturalist, as they are the last remnants of forms which were once abundant in the seas of past times. SUBCLASS II.—ARACHNIDA. With few exceptions, the Arachnids are terrestrial forms. They breath


Elements of comparative zoology (1904) Elements of comparative zoology elementsofcompar1904king Year: 1904 232 SYSTEMATIC ZOOLOGY. These forms live in the sea, feeding on worms, etc., found in the sea-bottom, coming to the shore in spring and early summer to lay their eggs. The horseshoe crabs are without any economic importance, as they are useless as food, but they are extremely interesting to the naturalist, as they are the last remnants of forms which were once abundant in the seas of past times. SUBCLASS II.—ARACHNIDA. With few exceptions, the Arachnids are terrestrial forms. They breathe by internal lungs or by tracheae, and they lack compound eyes. There are several orders of Arachnids, but only a few of them need be mentioned here, as some are inconspicuous, while others occur only in the warmer regions of the globe. ORDER I.—SCORPIONIDA. The scorpions have a single pair of jaws (mandibles) and a pair of large pincers, much like those of lobster or FIG. 60.—Under surface of scorpion (Buthus} showing the combs and outlines of the lung-sacs. crab. The long abdomen is distinctly jointed, the seven basal joints being much larger than the terminal five. The abdomen ends in a very efficient poison-sting. On the


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