PANTOPODA OR PYCNOGONIDA. 



379 



seaweeds and hydroids near the shore, but some live at great depths. 

 The body consists of an anterior proboscis, cephalothoracic region 

 with three fused and three free segments, arvd an unsegmented rudi- 

 mentary abdomen. Four some- 

 what primitive eyes on an anterior 

 hillock, are nearer to the eyes of 

 Arachnoids than to those of any 

 other class. There are typically 

 seven pairs of appendages. The 

 first are short and chelate, but 

 may be absent in the adult. 

 The next two are small and 

 slender, and are often absent in 

 the adult female ; the second pair 

 may also be absent in the male, 

 but the third in the males of all 

 genera carries the eggs. The 



last four pairs of appendages are FIG. 203. Sea-spider (Pycnogonum 

 always present, and form the littorale), from the dorsal surface, 

 walking legs. Into them, and 



into the chelicerse when these are present, out-growths of the mid-gut 

 extend. The sexes are separate. The larvae are at first unsegmented, 

 with three pairs of appendages. 



FIG. 204. Male of Nymphon. After Sars. 



PR., Proboscis ; C7/., chelophores ; P., pedipalps ; ., eggs carried on 



ovigerous legs ; A., rudimentary abdomen. 



Examples. Pycnogonum, Nymphon, Ammothea. In Pentanymphon 

 and Decolopoda there is an extra pair of long walking legs. 



