No.399] WORTH-AMERICAN INVERTEBRATES. 227 
d. Terminal segment regularly and broadly rounded at its 
extremity, with small median tooth. 
Idotea wosnesenskii Brandt, APD, surface to 9 fms. 
d'. Terminal segment acute or distinctly toothed at its 
extremity. 
e. With prominent post-lateral angles or teeth on 
either side of median tooth. 
f. With acute lateral teeth. 
Idotea marina (Linn.), VM, surface to 119 fms. 
f. With rounded lateral lobes. 
g. Epimera of second, third, and fourth 
segments short, not reaching the post- 
lateral angles of their respective seg- 
ments. 
Idotea ochotensis Brandt, A, surface to 18 fms. (See Fig. 10, p. 225.) 
g. Epimera of all the segments reaching the , 
postlateral angles of their respective 
segments. 
À. Sides of thorax arcuate 
Jdotea stenops Benedict, D 
h’. Sides of thorax more nearly parallel. 
Idotea whitei Stimpson, PD 
e’. With sidesssloping regularly to produced extremity. 
Idotea phosphorea Harger, N, surface to 18 fms. 
Genus Synidotea Harger. 
a. Terminal abdominal segment emarginate or notched at its extremity. 
b. Two spines or tubercles overhanging the frontal notch. 
c. Spines united near the base 
Synidotea pallida Benedict, A, 695 fms. 
c. Spines free at base. 
Synidotea erosa Benedict, A, 483 fms. 
P. No spines or tubercles overhanging the frontal notch. 
c. With a low ridge arising between the eyes and interrupted 
on the median line. 
d. Outlines of abdomen subparallel. 
Synidotea nebulosa vH A, 9-32 fms. 
d'. Outlines of abdomen strongly arcuat 
Synidotea angulata esit AP, 31-38 fms. 
c. Without a ridge between the eyes. 
d. Outline of abdomen subtriangülar. 
e. Front not excavated. 
Synidotea consolidata (Stimpson), P 
g. Front excavated. 
f. Outlines of thorax subparallel. 
Synidotea marmorata (Packard), JV, 36-129 fms. 
