86 
GAMMARIDiE. 
lessened in diameter. The eyes are moderately large, 
somewhat reniform, and of a black colour. The upper 
antennae are equal in length to the head and first two 
segments of the body taken together ; the peduncle has 
the first joint as long as the upper margin of the head, 
the second and third joints are successively shorter; the 
flagellum, which consists of six or seven articuli, is 
shorter than the peduncle, but the secondary appendage 
is nearly as long, though much more slender, than the 
peduncle. The lower antennae have the peduncle as 
long as the upper organs ; the first four joints are very 
short, but the fifth reaches to the extremity of the 
upper antennae ; it is of a peculiar shape — narrow near 
the base, it suddenly enlarges, leaving a hollow upon 
the lower margin, that enables the antennae at this joint 
to be reflected back upon itself, and thus the organ is 
carried, close pressed beneath the body of the animal, 
which is its usual position ; from the widest diameter, 
which is at the extremity of this hollow or notch, the 
joint gradually tapers to the apex. The flagellum is 
very slender and long, reaching much beyond the ex- 
tremity of the animal. Each articulus of the flagellum 
is a little longer than broad, and carries upon the upper 
margin, which is slightly raised near the centre for that 
purpose, a small membranous vesicle, in form like an 
inverted shoe, from which resemblance Mr. Stimpson, 
the naturalist of the United States’ Expedition to Japan, 
has given it the name Calceoia. The use of these organ- 
isms is not known ; Mr. Stimpson has, however, informed 
us that they are peculiar to the males ; whilst our expe- 
rience tells us that they are not common to the males of 
all Amphipoda, nor, in fact, to those of this genus ; 
neither do they appear to be so common to species which 
belong to the British seas as to exotic forms. 
