160 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
A 5. Third joint of outer ramus of second to fourth foot with 2 spines on external border, the distal 
one inserted on tip of border; terminal bristle of joint with broad, smooth edge * Cal anus 
Third joint of outer ramus of second to fourth foot with 3 spines on outer border, the distal one 
of which is inserted at tip of border; terminal bristle of joint denticulate (sometimes 
faintly) on its outer edge A 6 
The 3 spines on outer margin of third joint of outer ramus of second to fourth foot and the 
denticulation of terminal bristle obsolete Augaptilus (in part). 
A 6. One bristle of left limb of furca much longer and thicker than other bristles of furca A 7 
Furcal bristles symmetrical A 8 
A 7. Mandibular blade with 3 or 4 teeth, of which the ventral one is uncinate and separated 
from others by a long diastema; inner ramus of maxilla rudimental Heterochieta 
Mandibular blade with at least 8 teeth; inner ramus of maxilla well developed .Disseta 
A 8. Abdomen with 3 to 4 segments ; first segment with genital opening on its convex ventral surface. 
Anterior antennae symmetrical A8 2 
Abdomen with 5 segments (anal segment, however, sometimes obsolete) ; its first segment with 
lateral genital opening. One of anterior antennae a geniculating prehensile organ A 8 $ 
A 8 2 Inner and outer rami of fifth foot 3-jointed A 9 2 
Inner and outer rami of fifth foot 2-jointed Augaptilus (in part) 
Outer ramus of fifth foot 3-joiuted, inner ramus 2-jointed Isochata 2 
Outer ramus of fifth foot 3-jointed, inner ramus 1-jointed Isias 2 
Outer ramus of fifth foot 3-jointed, inner ramus lacking Phyllopus 2 
A 9 2 Second joint of outer ramus of fifth foot with a stout, thorn-like process on its inner border; 
third joint with 4 inner and 1 terminal bristle; third joint of inner ramus of fifth foot with 
6 bristles * Centropages 2 
Second joint of outer ramus of fifth foot with a thin, awl-shaped inner bristle; third joint of 
same with 3 inner and one terminal bristle; third joint of inner ramus of the fifth foot with 
5 bristles Leuclcartia 2 
Second joint of outer ramus of fifth foot with a thin, awl-shaped, or very rudimental inner 
bristle; third joint of same with 3 inner and 1 terminal bristle; third joint of inner ramus 
of fifth foot with at least 6 bristles A 10 2 
A 102 Abdomen with 4 segments; inner ramus of maxilla at least 1-jointed Hemicalanus 2 
Abdomen with 3 segments ; inner ramus of maxilla lacking Augaptilus 2 
A 8<? Right anterior antenna prehensile A 9 $ 
Left anterior antenna prehensile A 11 ^ 
A 9(J Both inner rami of fifth pair of feet 3-jointed, provided with plumose bristles A 10 $ 
Inner rami of fifth pair of feet rudimental, altogether without plumose bristles Isias $ 
A 10 ^ Outer rami of fifth pair of feet differing in structure, the right provided with forceps, the 
left 2-jointed; mandibular blade richly dentate ” Centropages $ 
Outer rami of fifth pair of feet of similar structure; mandibular blade with few 
teeth - Augaptilus $ 
A 11 1 Outer and inner rami of left fifth foot 3, of right 2-jointed Leuclcartia $ 
Both outer rami of fifth pair of feet 3-jointed, the inner rudimental, mamilliform. . . Arietellus $ 
Both inner and outer rami of fifth pair of feet 3-jointed A 12 $ 
A 12 (C Inner ramus of maxilla at least 1-jointed; distal bristles of anterior maxillipeds provided 
with points or naked Hemicalanus S 
Inner ramus of maxilla lacking; distal bristles of anterior maxillipeds with fungiform 
appendages Augaptilus £ 
A 13. Head with 2 large chitinons lenses, usually on edge of front, but sometimes shifted to ventral 
surface of the head ( Corycceidas) A 14 
Head without cliitinous lenses A 17 
A 14. Inner ramus of fourth foot (2- or) 3-jointed A 15 
Inner ramus of fourth foot 1-jointed or bristle-shaped A 16 
A 15. Abdomen with 4 or 5 segments, which are laterally dilated * Sapphirina 
Abdomen with 2 segments, which are not broadened Carina 2 
A 16. Eye lenses separated by a distance at least equal to their diameter; two last cephalothoracic 
segments without lateral projections, the last with a median dorsal spine Copilia 2 
Eye lenses close together; two last cephalothoracic segments prolonged into pointed lateral 
projections, last without a dorsal spine *Curyca:us 
