226 THE AMERICAN NATURALIST. (VoL. XXXIV. 
d. Legs subequal. Antenne geniculate. Palp of max- 
illipeds four-jointed. Body angulate. 
Erichsonella Benedict 
a’, Third and fourth pairs of legs usually markedly shorter. 
Fifth, sixth, and seventh pairs gradually increasing 
in length. Antenne not geniculate. Palp of max- 
illipeds two-jointed. Body slender, linear, smooth. 
Cleantis Dana 
Genus Chiridotea Harger. 
a. Species large, elongate-ovate. Outer branch of uropoda (or opercular 
valves) minute. 
ó. Joints of the peduncle of the antennz not dilated; flagellum 
eight to fourteen-jointed. Antero-lateral cervical lobes promi- 
nent. . Chiridotea entomon (Linn.), AP, surface to 15 fms. 
8’. Joints of the peduncle of the antennz greatly dilated ; flagellum 
seven to eight-jointed. Antero-cervical lobes prominent. 
Chiridotea sabinii (Krøyer), AN, surface to 15 fms. 
a’. Species small, orbiculate-ovate. Outer branch of uropoda at least half 
as long as inner. 
6. Antennz little longer than antennule ; flagellum seven-jointed. 
Eyes inconspicuous. Antennule longer than the peduncle of 
the antenne. . . . Chiridotea cecas (Say), NMS, surface 
8’, Antennz twice as long as antennule ; flagellum twelve-jointed. 
Eyes usually distinct. Antennulæ do not surpass the peduncle 
of the antenne. 
Chiridotea tuftsii (Stimpson), VM, surface to 25 fms. 
Genus Idotea Fabricius. 
4. Terminal segment emarginate at its extremity. 
Idotea resecata Stimpson, AD, surface 
a’. Terminal segment not emarginate at its extremity. 
Body slender, linear, filiform. 
c. Terminal segment truncate at apex. 
Idotea gracillima Dana, D 
c. Terminal segment not truncate at its extremi 
d. Post-lateral angles of terminal segment prominent and 
separated by a tooth from subtriangular middle por- 
tion, which bears a small tooth at the middle. 
Idotea urotoma Stimpson, P 
d'. Postlateral angles not separated by a tooth from 
middle portion. 
Jdotea rectilineata Lockington, D, 30-40 fms. 
&. Body oblong-ovate. 
c. Terminal segment truncate at its extremity. 
dotea metallica Bosc, NM, surface 91 fms. 
č. Terminal segment not truncate. 
