(20) 
P. exilipes , Stimpson. Rostrum nearly straight, seven or eight teeth 
above, one or two below. Hand of second pair of feet about two- thirds as 
long as carpus. 
FAMILY MYSIDAE. 
Feet more than five pairs, slender, often bearing palpi, none chelate, 
usually rudimentary on the abdomen. Gills wanting. 
Genus My sis. 
Six pairs of thoracic feet, each with two inany-jointed branches : three 
pairs of maxillipeds (12). Inner antennae with two flagella. Fourth pair of 
abdominal legs in male very long, styliform, directed backwards. 
M. relicta , Loven. Cephalo-thorax about one-third total length, 
broader behind than before. Pedicel (13) of inner antennae a little longer than 
the eyes, three-jointed, first joint about as long as second and third together. 
Inner flagellum shorter and more slender than outer. 
ORDER AMPH1PODA. 
Body commonly compressed, of fourteen segments ; thoracic segments 
not consolidated, eyes sessile if present. Gill plates thoracic. 
FAMILY ORCHESTIDAE. 
Upper antennae shorter than lower, no secondary flagellum (14). No 
palpus to mandible. Epimera (15) large. Last pair of abdominal legs not 
branched. 
Genus Hyalella. 
First two pairs of feet sub-chelate (16), the second the larger; upper 
antennae as long as peduncle of lower ; telson (17), short, stout, entire ; palpus 
of maxillipeds five-jointed ; first pair of maxillae with very short one-jointed 
palpi. 
H. dentata , Smith. First and second abdominal segments with a 
prominent tooth on middle of hind margin, second hand of male about three 
times as broad as first, flagellum of lower antenna commonly but little 
longer than that of upper. 
FAMILY LYSIANASSIDAE. 
Body little compressed, first two pairs of feet small and weak, epimera 
of first four segments very deep. 
Genus Pontoporeia. 
Upper antennae with short secondary flagellum ; first two pairs of legs 
very short, the first sub-chelate, the second not, seventh pair with basal joint 
very large. 
P. hoyi , Smith. First pair of hands with one to three small slender 
spines at tip of closed claw. About seven elongated papillae on the second 
to fifth segments of the sternum (18). Upper antennae short, about as long as 
head and first three thoracic segments ; flagellum about nine-jointed. 
P. filicornis, Smith. Upper antennae reaching nearly to tip of ab- 
domen, flagellum of about thirty-three joints, the terminal ones very long 
and slender. Secondary flagellum of four segments. 
