506 THE AMERICAN NATURALIST. [VoL. XXXIV. 
Hepatic region approximating the 
eye, its anterior margin transverse 
Batrachonotus 
H'. Spine of basal antennal joint advanced 
to the line of the front or nearly so. 
Hepatic region distant from the 
eye, its anterior margin oblique 
Euprognatha 
Cc’. Rostrum composed of two long spines : . Oregonia 
A’, Basal joint of antennz not extremely slender, often very | bindd Eyes 
with orbits, or capable of concealment. 
B. Basal joint of antenne truncate-triangular. Eyes without true 
orbits; eyestalks very short, either concealed beneath a supra- 
ocular spine or sunk in the sides of a huge beak-like rostrum. 
C. Antenne concealed beneath the rostrum. 
D. Rostrum formed of two long contiguous horns 
Sphenocarcinus 
D’. Rostrum not formed of two long contiguous horns. 
E. Eyes immovable . . UE VT, MOOR 
E. Eyes movable . . . Epialtus 
C. Antenne not concealed incid the rostrum. 
D. Entire lateral portion of carapace y acer Carapace 
smooth or nearly so . . Mimulus 
D’. Carapace with two large job c or teeth on each side. 
Carapace tuberculate . . . Pugettia 
B’. Basal joint of antenna broad, usually either bciliivay produced , 
outward or, often, with one or two distal spines. Eyes with 
its. 
C. Orbits with a large, blunt, cupped postocular process into 
which the eye is retractile, mat) is not completely concealed. 
Eyestalks short. 
D. No preocular spine 
E. Meral joints of ambulatory legs flattened. 
F. Carapace nearly as broad as long; suríace 
uneven . Chioncecetes 
F*. Carapace ide Igi ine bros; surface 
smooth Pelia 
E'. Meral joints of SDNY jan subcyliodricil ü 
as 
IX. A preocular spine. 
E. Ambulatory legs armed with spines . . . Nibilia 
E'. Ambulatory legs not armed with spines. 
F. Basaljoint of antenna deeply concave; second 
and third joints flattened, with thin, broad, 
lateral expansions. . . Scyra 
