308 : 6. 0. SARS, [N. s. 1Y 
sist each of a thick muscular peduncle and a very slender filiform flagellum. 
The peduncle is bent at the base in a geniculate manner, and is composed 
of 4 well-defined joints, the first 3 of which are rather short, whereas the 
last joint is very large and somewhat compressed, tapering gradually towards 
the tip. It is provided along the inferior edge with numerous transverse 
rows of delicate sensory bristles, and exhibits in its interior several strong 
muscles joining the base of the flagellum. The latter is divided into a number 
of distinet articulations (about 22 in all), which are rather elongated and 
provided along the inferior edge with tufts of small sensory bristles. Most 
frequently these antennæ are carried in such a manner as to be nearly 
hidden. In this case the peduncle is received between the greatly expanded 
antero-lateral corners of the carapace, and the flagellum applies itself 
closely within the inferior edge of the carapace and of the epimera of the 
exposed segments of the trunk; its remaining part, too, is received within a ` 
groove extending along the ventral side of all the segments of the metasome, 
and thus only the extremities of the flagella project freely at the end of the 
body, between the uropoda. By the aid of the strong muscles of the peduncle, 
these antennz can, however, be moved out from the body at any angle with 
the same, and are not infrequently found, in alcoholic specimens, stretched 
out in quite the opposite direction. 
The oral parts do not differ in any manner from those in the female. 
The gnathopoda are also of a very similar structure, with the exception 
that the basal lamellz of the anterior ones do not exhibit any trace of mar- 
ginal sete, and that the basal joint of the posterior ones is comparatively 
larger and more expanded at the base, in concordance with the much stronger 
development of the exopodite. : 
Of the legs not only the 2 first pairs, but also the 3rd and 4th pairs are 
provided with natatory exopodites. The latter appendages are much more fully 
developed than in the female, having the basal part very broad and lamellar, 
and the outer half of the flagellum divided into a great number of short ar- 
ticulations, each bearing a pair of densely ciliated natatory setze (see figs 
6—8). Owing to this powerful development of the exopodites the basal joint 
of all the legs, excepting the last pair, is mueh dilated, to receive the strong 
muscles moving these appendages. The 3rd and 4th pairs especially (figs. 6 
and 7) thereby acquire an appearance very different from that of the female. 
The 2nd pair of legs (fig. 6) differ also in other respects considerably 
from those in the female. They are considerably larger, not much shorter 
than the first pair, and have the carpal joint much elongated, fully twice 
as long as the 2 preceding ones combined, and provided on both edges with 
several short plumose setæ. Finally the terminal joint (fig. 6) is highly re- 
Mélanges biologiques. T. XIII, p. 472. 
