ISOPODS OF NORTH AMERICA. 4VH) 



e. vSixth abdoiiiinal Kegineiit in male with post-lateral angles produced in 



long processes Genus Cnjptionc Hansen 



e^. Sixth abdominal segment in male with post-lateral angles not produced 



in long processes Genus Fseudione Kossmann 



c\ Lateral parts or pleural lamella- of alidomen of female rudimentary or absent. 

 (/. Pleopods present in female. 



e. Some or all of pleopoda in female tri-ramous. 

 /. All the pleopoda in female tri-ramous. Sixth segment of thorax greatly 

 longer than any of others. Uropoda in female oval, with a small 



conical process between them Genus Steyoplirii.ms Thompson 



f. First three pairs of pleopods tri-ramous; last two pairs bi-ramous. 

 Sixth segment of the thorax not greatly longer than any of the 

 others. Uropoda elongated, with no process between them. 



Genus Steglas Richardson 

 e^. None of pleopoda tri-ramous in female. 

 /. Pleopoda bi-ramous in female. 

 g. Uropoda present in female. 



h. Uropoda bi-ramous in female Genus Bafln/gnge Hansen 



//. Uropoda simple, .single-branched' in female. 

 i. Both branches of pleopoda in adult female similar in size and 

 shape, narrow, elongated. Male with segments of abdomen 

 distinct and with a pair of elongated appendages to each of 

 the first five segments. Uropoda present in male, single- 

 branched. First abdominal segment in both sexes furnished 



with two dorsal papilhe Genus Phyllodurus Stimpson 



V. Branches of pleopoda in adult female unlike; outer branch 

 narrow, elongated; inner branch oval, small. Male with seg- 

 ments of abdomen fused and without any appendages to the 

 abdomen; without uropoda. First al)dominal segment in both 

 sexes not furnished with two dorsal papilhe. 

 j. Posterior lobe of lateral margins of all the segments of the 

 thorax more or less produced into processes. Abdomen of 

 male narrow, tapering, not furnished with dorsal tubercle. 



Genus Argcia Dana 

 j\ Posterior lobe of lateral margins 9f thoracic segments not pro- 

 duced into processes. Abdomen of male large, rounded, 

 and furnished with a prominent median dorsal tubercle 



near the base Genus Parargela Hansen 



(/'. Uropoda wanting in female. 

 7i. Segments of abdomen fused in male. Segments of abdomen dis- 

 tinct in female Genus Prohopyrna Giard and Bonnier 



//. First three segments of abdomen distinct in male; last three seg- 

 ments fused. First four segments of abdomen distinct in female; 



last two segments fused Genus Bopgrm-m, new genus 



f. Pleopoda simple, single-branched in female. 



( lenut^ Bopgriiia Kossmann. 

 (I\ Pleopoda wanting in female Genus Bopyruidesi Stimpson 



81. Genus PHRYXUS Rathke." 



Abdominal para.-iites. 



Body of feiiude very a.syiniiietrical, one .side beino- very niurli laroer 

 than the other. 



«See Sars for characters of genus, Crust, of Norway, II, 1899, pp. 214-215. 



