240 
HORN EXPEDITION—CRUSTACEA. 
scarcely defined in the female from the frontal region, hut in the male forming a 
well-marked angle with it. Legs thirty-two pairs in both sexes. Telson about 
equal in length to the .seven preceding segments of the abdomen, and with very 
many anal denticles. 
The shell-gland is clearly visible, takes its origin at the place where the 
adductor muscle joins the inner face of the valve and reaches backwards and 
downwards to about half the distance between the dorsal and ventral margins of 
the carapace. 
The part of the body in front of the umbonal region is abruptly deflexcd, the 
doDsal line running vertically downwards for about 3-o mm., forming the so-called 
cervical segment. From the latter the head is sharply marked oflT. The head is 
very different in the two sexes. In the female, seen from the side, the dorsal 
margin is bent at an acute angle, which is occupied by the eye. The lower edge 
is directly continuous backwards with that of the rostrum, which is small in the 
female. The haft-organ is situated midway along the upper edge, and is pear- 
shaped, being attached by its smaller end. The division between the two eyes is 
just visible. In the male the head is not so massive as in the female; rostrum bent 
at right angles to the lower surface of the head, and very prominent. The pro¬ 
jection bearing the eyes is more clearly marked off' from the head than in the female. 
First antenna} much smaller in the female than in the male, and in both sexes 
very irregularly jointed. In the female they ai’e as long as the proximal undivided 
part of the second antenme. Lower edge of antennule straight, upper edge pecti¬ 
nate, with sixteen small, blunt, rounded pi’ojections. In the male the antennule 
reaches some distance beyond the level of the proximal undivided part of the second 
antenna}, the pectinate projections being more prominent than in the female. 
The second antenme consist each of a proximal and a distal portion. The 
former is unjointed, and is pectinated on its upper edge, the projections being about 
eleven in number. These projections correspond to transverse lines on the inner 
face of the basal portion, which divide the inner face into a series of segments. 
A few plumose setie arise from the denticles. The distal portion consists of two 
rami, the upper being slightly shorter than the lower. Each ramus is divided into 
a series of joints, which may be as many as eighteen in number in the lower. Each 
joint bears on its upper surface a number of short, stout seta}, and on its under 
surface a larger number of long plumo.se seta}. Labrum running backwards and 
upwards, ending bluntly and bearing just before its termination a small setose 
projection. 
