BEVIEW OF GENUS ARGULUS — MEEHEAN 



501 



segments are only as long as the coxa of the second one; coxa with 

 a bilobed papilla on the anterior surface; basis short and mnnodi- 

 fied. The first segment of the endopod is very broad, with a spine 

 in the middle of the ventral surface and a longer sharper one on the 

 anterior distal surface at the base of the distal segment. The distal 

 segment is curved, with long curved setae that fold over from both 

 edges, which are peculiar in that they bend toward the posterior of 

 the segment and are found on both edges instead of only one as in 

 other species. The exopod originates on the dorsal surface of the 

 basis and curves laterally reaching to the middle of the distal segment 

 of the endopod. The socket can be seen from the dorsal side as a 

 lobe rounded posteriorly from the coxa (fig. 36, c). 



FiGDEB 36." 



-Argulus violaceus: a. Ribs of suction cups ; 6, respiratory areas ; c, accessory 

 organs of tbird and fourth legs of male. 



The fourth appendages have a slight rounded lobe on the posterior 

 of the coxa. Anteriorly there is a slight indication of a chitinous 

 ridge around the base of the peg. The peg is a mounded, button- 

 shaped, chitinous papilla, with a slight concavity on the top. The 

 exopod originates on the dorsal side of the basis as on the third 

 appendages, with a triangular flap over the peg, as seen from the 

 dorsal side. The basal segments of the fourth appendages are cov- 

 ered by the abdomen. 



The female is 6.5 mm. and male 5 mm. The hosts are Pledostomus 

 com/mersonii from Uruguay and Rhamdia quelea. 



