50 THE VOYAGE OF H.M.S. CHALLENGER. 
first segment of the body is considerably swollen at the base of the mandibles, constricted 
posteriorly, and shows a faint line at the beginning of the first true thoracic segment. 
The abdomen is comparatively long. The upper surface of the body is armed with 
numerous spines, forming in the middle of the segments star-like groups (Pl. IV. fig. 12), 
and scattered more irregularly on the lateral processes; near the end of these a row 
of stronger spines is observed. The oculiferous tubercle is, especially in the females, 
highly elevated, and shows four dark eyes separated by a cross-like spot. The oculiferous 
tubercle is placed on the cephalic part of the first segment, between the two ovigerous 
legs. 
The mandibles are very long, the first joint being much longer than the proboscis; ° 
the second joint is shorter and strongly curved, the claws being placed almost trans- 
versely before the mouth. The immovable claw is more strongly curved than the 
movable one; the spines on the claws are numerous, but they are almost equal and of 
the same length. Both joints are covered with numerous small hairs, stronger ones being 
found at the end of the first joint (Pl. V. fig. 2). 
The palpi are not very hairy. The second joint is by far the longest, the fourth is 
the shortest, the fifth very slender. The whole length of the palpus is about twice the 
length of the proboscis (PI. V. fig. 1). 
The ovigerous legs of the males are not quite so long as the body. The fifth joint 
is the longest, and is considerably swollen at the extremity, the sixth joint is a great deal 
shorter, the seventh to the tenth joints are very short, the claw almost of the same length 
as the last jomt. The ovigerous legs are very strongly bent and not very hairy. The 
denticulated spines of the four last joints are sharply serrated and not numerous, their 
numbers being respectively 3, 3, 2, 3 (Pl. V. figs. 3, 4). The claw is furnished with a 
row of acute spines. 
The ovigerous legs of the females are still shorter than those of the males, The - 
relative length of the joints is the same, but the fifth joint is not swollen at the 
extremity. The leg is not curved as is the case with that of the male. 
For a species of Nymphon the true legs are uncommonly short: a female of 6 mm. . 
has a leg of only 14 mm. The second joint is not quite twice as long as the first or 
third, the three following joints are almost of the same length and comparatively robust, 
especially the fourth joint of the female. The two tarsal joints, the second of which is 
the longer, are very slender and almost smooth, together about as long as the sixth joint. 
The claw is about as long as one-third of the length of the second tarsal joint, the auxiliary 
claws are very small. The legs are very hairy. These hairs vary greatly in size and 
strength, and are not placed in regular rows. The dorsal surface of the leg especially is 
covered by a large quantity of stronger spines. The genital pores of the females are very 
large and visible on the second joint of every leg. Those of the males are small, and 
found only on the second joints of the two last legs. 
