306 THE AMERICAN NATURALIST. [Vor. XXXIV. 
FAMILY XXI. LIGIDÆ. 
a. Uropoda with branches equal in length, styliform, often filiform. In- 
terior mala of the mandibles with numerous pencils of hairs. Last 
segment of body broad, with distinct epimeral plates. Maxillipeds 
with palp 4—5-jointed ; epignath rounded. . . . Ligia Fabricius 
a’. Uropoda with branches unequal in length. 
é. Extremity of uropoda furnished with two long apical bristles. In- 
terior mala of the right mandible with three pencils of hairs, of 
the left mandible with five pencils of hairs. Last segment of 
body small, and without any epimeral plates. Maxillipeds with a 
five-jointed palp; epignath narrow, linguiform. Ligidium Brandt 
/. Extremity of uropoda not furnished with two long apical bristles. 
. Styloniscus Dana 
Genus Ligia Fabricius. 
4. External antennz shorter than the body. 
4. Uropoda about equal to half the length of the body. 
Ligia occidentalis Dana, D, Littoral 
&. Uropoda not equal to half the length of the body. 
c. Uropoda equal to one-fifth i length of the body. 
igia pallasii Brandt, AP, Littoral 
c. Uropoda nearly equal to Bonum the length of the body. 
igia oceanica (Linn.), W, Littoral 
a’, External antennz longer than body or equal to length of y. Uro- 
poda about equal to two-thirds the length of body. 
Ligia exotica Roux, D, Littoral 
Genus Ligidium Brandt. 
a. Inner process of the basal article of the uropoda three times shorter 
than the external terminal branch; internal terminal branch reaching 
the apex of the external branch; the two terminal hairs equal in 
length to the external branch. 
Ligidium hypnorum (Cuvier), P, Littoral 
a’. Inner process of the basal article of the uropoda four times shorter 
than the external terminal branch; internal terminal branch long, 
extending much beyond the apex of the external branch, being a sixth 
part longer; the two terminal hairs short, equal in length to half the 
external branch. . . Ligidium tenue Budde-Lund, A, Littoral 
Genus Styloniscus Dana . CM A gracilis Dana, California, Littoral 
Genus Euphiloscia Packard. . . Euphiloscia elrodit Packard, Indiana 
This genus probably belongs here. 
FAMILY XXII. TRICHONISCIDA. 
a. Abdomen abruptly narrower than thorax. Head rounded in front, with 
distinct, though small lateral lobes. Terminal abdominal segment 
truncate attip . . . . «+ . Trichoniscus Brandt 
