300 THE AMERICAN NATURALIST. [Vor. XXXIV. 
6. Front of head three-lobed, the center lobe subacute, rather longer 
than others, but not rostrate. . Janira occidentalis Walker, P 
&. Front of head produced in the middle in a short, sharp rostrum, and 
the antero-lateral angles of head also produced. 
c. Antero-lateral angles of head sharp. Lateral margins of first 
four thoracic segments obtusely incised, each showing two 
broad angulations. Uropoda of female shorter than half the 
terminal segment; those of male as long as terminal segment 
of body . . . Janira tricornis (Krøyer), JV, 5-50 fms. 
c. Antero-lateral sates of the head shorter and less sharp. Mar- 
gins of the first thoracic segment rounded, not emarginate. 
Uropoda alike in the two sexes, and as long as the terminal 
segment of the body. 
ints alta (Stimpson), W, 35-300 fms. 
Genus Jaropsis Koehler . . . . . Jeropsis lobata Richardson, D 
FAMILY XVII. MUNNID2. 
Genus Munna Krøyer. 
a. Caudal segment, with lateral edges evenly convex, and each armed with 
a single slender denticle ; apical lamelle distinctly serrated. Eyes 
large. Superior antennae, with flagellum composed of four joints, 
including very small apical joint. Flagellum of inferior antenne 
longer than peduncle. Last pair of legs scarcely longer than body. 
Legs slender. Uropoda obliquely truncate at tip. 
unna fabricii Krøyer, W, 12-200 fms. 
a’. Caudal segment, with lateral edges rather bulging in front, and each 
armed with four strong denticles; without any serrulated lamellz. 
Eyes small. Superior antennz, with flagellum composed of three 
articulations, including very small apical joint. Flagellum of inferior 
antennz not attaining the length of the peduncle. Last pair of legs 
scarcely longer than anterior division of body. Legs shorter and 
stouter than usual. Uropoda produced at tip into several dentiform 
projections, one of which is hook-like. 
Munna kréyeri Goodsir, JV, 10—60 fms. 
FAMILY XVIII. MUNNOPSID. 
a. Head of moderate size, deeply emarginate on each side for the insertion 
of the antennz ; frontal part produced. First four thoracic segments 
transversely excavated dorsally. Superior antennz, with flagellum 
multi-articulate. Natatory legs of the same structure, carpal joint 
s. 
ő. Body, with anterior division much broader than posterior ; three 
posterior segments densely crowded together. Caudal segment 
