594 BULLETIN 159, UNITED STATES NATIONAL MUSEUM 



98. Second antenna 5-segmented, with a 2-segniented exopod 



attached to its second segment; first antenna 18-seginented; 

 urosome 3-segmented, last 2 segments very short; inverte- 

 brate washings ? Cletopontius Thompson and Scott, 1903 



Second antenna 4-segmented, with a 1-segmented exopod at- 

 tached to its second segment 99 



Second antenna 3- or 4-segmented, without an exopod 101 



99. Urosome 3-segmented, completely covered by last metasome 



segment; fifth leg fifteen times as long as v/ide, with hairy 

 margins and 3 setae; oyster washings. 



9 Lepeopsyllus Thompson and Scott, 1903 

 Urosome entirely free dorsally ; fifth leg as wide as long 100 



100. Head wider than long; sucking tube reaching posterior margin 



of head; distal segment of first exopod with 2 spines and 4 



setae; littoral, among algae cf 9 Dyspontius Thorell, 1859 



Head longer than wide; sucking tube reaching posterior margin 

 of metasome; distal segment, first exopod with 3 spines and 

 5 setae; dredged, 40 fathoms cf 9 Cryptopontius Giesbrecht, 1899 



101. Urosome fused into a single segment; head with ventral beak; 



fourth segment with sharp processes at the posterior corners; 



pelagic, at surface cf 9 Corycella Farran, 1911 (p. 361) " 



Urosome 4-segmented in female, 5-segmented in male; no 

 beak; all body segments except last 2 with epimeral plates, 

 front ones crenate; parasitic cf 9 Pteropontius Giesbrecht, 1895 



102. Metasome inflated into a sphere; first and second antennae of 



equal length, the latter 2-segmented, with accessory claw; 



fifth legs lacking; gills of fishes cf 9 Thersitina Norman, 1905 



Metasome cyclopoid, twice as long as wide; second antenna 



twice as long as first, 3-segmented, without accessory claw; 



fifth legs 1-segmented; pelagic cf 9 Limnoncaea Kokubo, 1919 



Metasome cylindrical or flattened; second antennae four to 



eight times as long as the first pair 103 



103. Urosome 2-segmented in female, 3-segmented in male; second 



antenna seven or eight times as long as first pair; fifth leg 

 a tiny knob with 1 seta (Lake Tanganyika). 



cf 9 Ergasiloides G. O. Sars, 1909 

 Urosome 4-segmented in female, 5-segmented in male; second 

 antenna four or five times as long as first pair; fifth leg 

 1-segmented, with 2 apical setae; gills of fishes. 



cf 9 Ergasilus (part) Nordmann, 1832 (p. 375) 



104. Fourth leg uniramose, 1-segmented; first antenna 5-segmented; 



second antenna 4-segmented, with no exopod; end segment 

 with 3 unequal apical claws; parasitic on annelids. 



cf 9 Chonephilus M. Sars, 1861 

 Fourth leg uniramose, 3-segmented; first antenna 18-seg- 

 mented; second antenna 5-segmented, with 2-segmented 

 exopod; end segment with 2 unequal end claws; washings 

 of invertebrates 9 Cletopontius Thompson and Scott, 1903 



105. Metasome with epimeral plates on one or more segments 106 



Metasome with no epimeral plates on any segment 108 



3« Corycella was used by Leger for a genus of Protozoa in 1893. Blake has suggested in manuscript the 

 name Farranula in place of it. 



