PARASITIC COPEPODS — ^WILSON 577 



body one-fourth longer than wide; anterior respiratory area as 



wide as iwsterior but very much shorter flavescens 



e*. Ribs of suction cups made up of irrrbricated plates with or without 

 a long basal segment. 

 /\ Ribs of suction cups made up of imbricated plates; postantennal 

 spine broad and blunt. 

 g '. Imbricated plates 30 or more ; knob present on anterior margin 

 of first antennae; maxillae slender__ melanostictus (p. 565) 

 g I Imbricated plates 15 to 20 ; carapace reaching abdomen ; anter- 

 ior hook present on anterior margin of first antennae. 

 ft.\ Flagella present; basal maxillary plate with a boss covered 

 with spines; end segment of maxilliped half as large as 

 penultimate segment; tipped with 3 sharp claws; second 

 antenna 5-segmented, second segment as long as 



third pugettensis 



h'. Flagella present; maxillipeds exceptionally stout, basal plate 

 without a boss, end segment 3 times as large as penultimate 

 segment; second antennae 4-segmented, third segment 9 



times as long as second niger* (p. 569) 



h '. No flagella ; maxillipeds normal size ; proximal tooth on basal 

 plate widened; respiratory areas nearly equal in size; 

 supporting ribs made up of 19 tiny segments; segments of 



second antennae equal floridensis 



f ■. Ribs of suction cups made up of long basal segment and imbri- 

 cated plates. 

 g \ Swimming legs without flagella. 



h \ Respiratory areas small and widely separated ; basal segment 

 of supporting ribs narrow and elongate ; posterior lobe of 

 fourth leg somewhat bilobed ; knob on anterior margin of 



first antenna borealis 



h -. Respiratory areas normal, one large, one small. 

 i \ Spines on basal maxillary plate alike ; jwsterior respiratory 

 area regular; supporting ribs made up of 1 long and 9 

 imbricated segments ; jwsterior lobe on fourth leg boot- 

 shaped ; basipod of third leg in male with curved spine 

 at anterior corner; basipod of fourth leg with spherical 



peg megalops (p. 563) 



i '. Spines on basal maxillary plate alike ; posterior respiratory 

 area symmetrical ; supporting ribs made up of 1 long basal 

 and 3 distal segments not imbricated; lobe on fourth leg 

 without a toe ; second male basipod with 2 posterior proc- 

 esses ; fourth basipod with conical peg. 



trilineatus* (p. 566) 



« *. Spines on basal maxillary plate alike ; posterior respiratory 



area symmetrical ; ribs of suction cups made up of 4 



quadrangular segments; ventral surface of maxilliped 



covered with scales varians* (p. 570) 



i*. Spines on basal maxillary plate unlike, lateral one blunt, 



the others more pointed ; anal sinus deep. 



/\ Suction cups occupying almost full width of carapace; 



supporting ribs made up of 6 to 10 imbricated plates 



and a rectangular basal segment; larger respiratory 



area widened posteriorly blcolor 



658871—44 ft 



