136 THE AMERICAN NATURALIST. | [Vor. XXXIV. 
J. Terminal segment of abdomen of 
male oblong.  Carapace sub- 
quadrate, narrow (length about 
three-fourths width), approach- 
ing the Catometopa. Prominent 
transverse dorsal ridges 
Rhithropanopeus 
J'. Terminal segment of abdomen of 
male subtriangular. Carapace 
when subquadrate, wider than 
the preceding. 
K. Front arcuate. Carapace 
hexagonal | Neopanope 
K'. Front with truncate or sinu- 
ous lobes 
L. Front very narrow and 
advanced. Postero- 
lateral margins 
strongly converging. 
Carapace hexagonal 
exapanopeus 
L'. Frontof moderate width. 
Postero-ateral mar- 
gins not strongly con- 
verging. Carapace 
subquadrate 
Eupanopeus 
A’, The ridges that define the efferent branchial channels extend to the 
anterior boundary of the buccal cavern and are often very strong. 
B. Fronto-orbital border just about half or less than half the greatest 
breadth of the carapace, which is broad and transversely oval. 
C. Antero-lateral margin much shorter than the postero-lateral. 
Front with two simple lobes . . Eurytium 
C. Antero-lateral and Pee hargin Fhia Front 
with two lobulate lobes . . Menippe 
B’. Fronto-orbital border much more tale half na: greatest breadth 
of the carapace. 
C. Carapace nodose . . . Lobopilumnus 
C. Carapace not nodose, but often n granulate or spinous, and 
usually hairy . . . . . > Pilumnus 
