No. 400.] MWORTH-AMERICAN INVERTEBRATES. 307 
a’ 
Abdomen not abruptly narrower than thorax. 
. Head rounded in front, not lobated at the sides. Abdominal epim- 
era but little developed — . . - Scyphacella Smith 
&. Head triangularly produced in front; with ices lateral lobes. 
Abdominal epimera lamellarly expanded. 
c. Body sculptured dorsally with more or less distinct longitudinal 
ribs. Terminal abdominal segment truncate at apex. Basal 
segment of the i Rie not simulating the epimera of the 
preceding segmen Haplophthalmus Schóbl. 
c&. Body not ipsc. done aiin abdominal segment 
rounded posteriorly. Basal segment of the uropoda simulating 
the epimera of the preceding segment . Actoniscus Harger 
Genus Trichoniscus Brandt. 
Trichoniscus pusillus Brandt, North America at Niagara 
Genus Scyphacella Smith . . . Scyphacella arenicola Smith, W, Beach 
Genus Haplophthalmus Schóbl. 
Haplophthalmus puteus Hay, fresh water, Indiana 
Genus Actoniscus Harger. . . Actoniscus ellipticus Harger, JV, Beach 
VI. EPICARIDEA. 
a. Body of female distinctly segmented, more or less asymmetrical, twisted 
either to right or left. Maxillipeds lamellar, biarticulate, and more 
frequently exhibiting a small terminal joint. Legs seven pairs, some- 
times obsolete on one side. Incubatory plates five pairs, more or 
less arching over the ventral surface of the thorax. Pleopoda form- 
ing simple or double lamellz, all of the same structure, rarely obso- 
lete. Male with all the segments of the thorax sharply defined. 
Last larval stage with the flagellum of the antennz 4-articulate ; 
legs of uniform structure; uropoda with inner branch shorter than 
outer. Parasitic on decapodous Crustacea. 
Family XXIII. Bopyrida 
a’. Body of female perfectly symmetrical, the segmentation only visible, as 
a rule, in the middle of the dorsal face. Maxillipeds lamellar, with- 
out any terminal joint. Only five pairs of legs present. Incubatory 
plates comparatively small, sometimes greatly reduced in number, 
and scarcely at all partaking of the formation of the marsupium, 
which constitutes two separate cavities, bounded by the lateral walls 
of the body itself. Pleopoda generally rudimentary or wholly absent. 
Male with head and first segment of thorax coalesced. Last larval 
stage with the flagellum of the antennz 5-articulate; legs of the 
first pair shorter and thicker than the others; uropoda with the 
branches subequal. Parasitic on Schizopoda. 
Family XXIV. Dajidz 
