. Outlines of zoology. about PANTOPODA OR PYCNOGONIDA. 375 seaweeds and hydroids near the shore, but some live at great depths.The body consists of an anterior proboscis, cephalothoracic regionwith three fused and three free segments, ard an unsegmented rudi-mentary abdomen. Four some-what primitive eyes on an anteriorhillock, are nearer to the eyes ofArachnoids than to those of anyother class. There are typicallyseven pairs of appendages. Thefirst are short and chelate, butmay be absent in the adult.The next two are small andslender, and are often absent inthe adult female; the second pairmay

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. Outlines of zoology. about PANTOPODA OR PYCNOGONIDA. 375 seaweeds and hydroids near the shore, but some live at great depths.The body consists of an anterior proboscis, cephalothoracic regionwith three fused and three free segments, ard an unsegmented rudi-mentary abdomen. Four some-what primitive eyes on an anteriorhillock, are nearer to the eyes ofArachnoids than to those of anyother class. There are typicallyseven pairs of appendages. Thefirst are short and chelate, butmay be absent in the adult.The next two are small andslender, and are often absent inthe adult female; the second pairmay also be absent in the male, but the third in the males of allgenera cirries the eggs. The last four pairs of appendages are FiG. 203.—Sea-spider {Pycnogonumalways present, and form the litiorale), from the dorsal surface, walking legs. Into them, and into the chelicerse when these are present, out-growths of the mid-gutextend. The sexes are separate. The larvse are at first unsegmented, with three pairs of appendages..