. Bulletin of the United States Fish Commission. Fisheries -- United States; Fish-culture -- United States. 294 BULLETIN OF THE BUREAU OF FISHERIES. and the brush is more conspicuous in older individuals than in the young. The tufts of seta which are found on the propodus of the young and adolescent males disappear gradually with successive molts, until their places in large individuals are marked by small pits. PLEOPODS. The pleopods of the male differ from those of the female (Fig. 269) in having only the outer limb, or exopodite, developed. Both exopodite and endopodite are devel- oped in t
. Bulletin of the United States Fish Commission. Fisheries -- United States; Fish-culture -- United States. 294 BULLETIN OF THE BUREAU OF FISHERIES. and the brush is more conspicuous in older individuals than in the young. The tufts of seta which are found on the propodus of the young and adolescent males disappear gradually with successive molts, until their places in large individuals are marked by small pits. PLEOPODS. The pleopods of the male differ from those of the female (Fig. 269) in having only the outer limb, or exopodite, developed. Both exopodite and endopodite are devel- oped in the female. The exopodites of the female are somewhat longer and broader than those of the male. The first endopodite is similar in shape to the exopodite, but the remaining three endo- podites are bifurcate, and in adult females they are fringed with long setae upon which the eggs are carried. These bifurcate endopodites are not colored, being com- posed of white, flexible chiti- nous material. The edges are reinforced with scutes from the undersides of which the long setae project in tufts. Some of these setse are plumose and shorter than the others which are nonplumose. The exopodites appear to the naked eye to be finely ribbed. These ribs appear under the microscope as dense, granular masses, along which at intervals are groups of minute setae. All of these groups of setae do not appear to be the same, some being composed of two or three comparatively long setae and one seta which is short. The longer setae are seg- mented and plumose, while the shorter seta is segmented and nonplumose. Nerve fibers extend through these setae, which indicates that they may be sense organs, but whether they receive tactile or chemical stimuli is not apparent. The bases of these setae are flask shaped, the distal portion of the segment being greatly enlarged. Other groups of setae are composed of three or four short setae, none of which are plumose. They may represent the remains of longer set
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