228 THE AMERICAN NATURALIST. [VoL. XXXIV. 
. Outlines of thorax strongly arcuate. 
Synidotea bicuspida (Owen), AN, 5-1314 fms. 
d'. Outlines of abdomen rounded. 
Synidotea laticauda Benedict, A, surface to 56 fms. 
a’. Terminal abdominal segment pointed at its extremity. 
6. Undulations of body not tubercular or spiny. 
c. Tubercle in front of eyes not margined. 
Synidotea nodulosa (Krøyer), AW, 16-119 fms. 
č. Tubercle on the frontal margin and forming a part of it. 
Synidotea levis Benedict, A, 29-36 fms. 
/. Undulations of the body tubercular and spiny. 
c. Four spines on the front of the head; body spinous. 
Synidotea muricata (Harford), A, 25 fms. 
c’. A wedge-shaped tubercle behind the frontal notch ; body 
tubercular. . . . Synidotea picta Benedict, A, 9 fms. 
Genus Colidotea Richardson . . . . Colidotea rostrata (Benedict), P 
Genus Edotea Guérin-Ménéville. 
a. Anterior angles of head produced into horn-like projections. Lateral 
angles of thoracic segments produced into horn-like projections. 
Four tubercles situated on dorsal surface of head. 
dotea acuta Richardson, JV, 105 fms. 
a’. Anterior angles of head not produced into horn-like projections. Lateral 
angles of thoracic segments not produced into horn-like projections. 
Two tubercles situated on dorsal surface of head. 
é. Lateral margins of thorax nearly even. Anterior angles of 
head not salient. Lateral margins of terminal segment 
scarcely indented. 
Edotea triloba (Say), NM, surface to % fm. 
2’. Lateral margins of thorax angulated and salient. Anterior 
angles of head salient. Lateral margins of terminal seg- 
ment indented ; terminal segment rather elongated. 
dotea montosa (Stimpson), NM, 2-40 fms. 
Genus Erichsonella Benedict. 
a. Surface of body smooth throughout. Outline of body regular. Anten- 
nule short. Terminal segment of body with but slight traces of a 
lateral tooth near its base on either side. 
Erichsonella attenuata (Harger), M 
a’. Surface of body tuberculated. Outline of body serrate. Antennule 
long. Terminal segment with a prominent lateral tooth near its base 
on either side. Large bifid tubercle on center of head. Median 
longitudinal row of tubercles on each thoracic segment. 
Erichsonella filiformis (Say), M, 4M to 7 fms. 
Genus Cleantis Dana. 
a. Flagellum consolidated and forming a single piece. Abdomen com- 
our segments. Terminal abdominal segment with rounded 
