No. 399] WORTH-AMERICAN INVERTEBRATES. 211 
Fic. 1. — Tanais alascensis. Fic. 2.! — Gnathia cerina. Fic. 3.! — Cyath arinata 
à. Abdomen composed of six segments. Body robust and tapering. 
Tanais robustus Moore, M 
&. Abdomen composed of five distinct segments. Body slender, 
elongated. | 
c. With transverse setiferous bands crossing first and second 
abdominal segments. Terminal segment with a blunt 
median projection.  Uropoda three-jointed. 
Tanais cavolinii Milne Edwards, V 
c. Without transverse setiferous bands crossing first and second 
abdominal segments. Terminal segment with slight me- 
dian notch. Uropoda seven-jointed. 
Tanais alascensis Richardson, A, 6-8 fms. 
Genus Cryptocope G. O. Sars. . Cryptocope arctica Hansen, JV, 170 fms. 
Genus Leptognathia G. O. Sars 
4. In female inner branch of uropoda twice as long as outer. The second 
or first free segment of thorax is about two-thirds as long as the third, 
which in turn is about equal to the fourth and fifth. Sixth and seventh 
segments are progressively somewhat shorter. Propodus of first pair 
of legs less robust than carpus. 
Leptognathia ceca (Harger), JV, surface to 48 fms. 
a’. In female inner branch of uropoda more than three times as long as 
outer. The second, or first free segment of thorax about same size 
as the last one, both being shorter pol = others. Propodus of 
first pair of legs scarcely smaller than c 
Leptognathia longiremus tienes AV, 35-40 fms. 
1 Figures taken from O. Harger. 
