48 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
side with a small spiniform tooth projecting forward, and the plane of 
the plate is much below the very narrow sternal plate at the bases of 
the external maxillipeds. The sternum of the last thoracie somite is 
entirely membranaceous, without any calcified plate or bar between the 
bases of the posterior legs. 
The abdomen is broad, evenly rounded above, and without longitudi- 
nal carine; the epimera are all very short; and the sterna of all the 
somites are almost entirely membranaceous, like that of the last thoracic 
somite. The dorsum of the first somite rises in a sharp and very nar- 
row transverse ridge back of the facet which slides beneath the carapax, 
and is inclosed either side by the anterior projection of the epimera of 
the second somite. The epimeron of the second somite is truncated 
below, but projects forward in a sharp angle at the side of the carapax, 
and above the angle is armed with a large, curved, and acute spine, 
directed forward above the lateral margin of the carapax. ‘The epimera 
of the third, fourth, and fifth somites are truncated, with the angles 
more or less rounded, and those of the sixth obtuse. The second and 
third somites are each marked above by two transverse ciliated ruge, 
the fourth and fifth each by three similar but less conspicuous rug in 
adults, or only two in the young, and the sixth somite and all the 
epimera are marked by broken and irregular ruge or squamiform ele- 
vations. The sixth somite is much longer than the fifth, about a third 
as long as broad, and the postero-lateral edge outside the articulation 
of the uropod is oblique and nearly straight. 
The telson in full-grown specimens is only as long as the sixth somite, 
and twice as broad as long, but in young specimens is proportionally 
longer and narrower. The whole appendage is thin and slightly,calei- 
fied; the lateral margins are deeply incised about the middle and the 
incisions connected by a transverse membranous articulation, so that 
the distal part is readily folded beneath the proximal. The distal part 
is notched at the middle of the posterior edge and longitudinally divided 
by a membranous line, so that it appears to be formed of two trans- 
verse elliptical plates, each nearly twice as broad as long, and of which 
the posterior and lateral edges are thickly ciliated. The inner lamella 
of the uropod is fully as long as the telson, about two-thirds as broad 
as long, elliptical, the inner and distal edges armed with spines, which 
are small on the inner and very minute and crowded on the distal edge, 
and the entire margin, except near the base, is ciliated with numerous 
long hairs. The outer lamella is longer and broader than the inner, 
narrowed and somewhat excavated on the inner edge near the nee 
and margined with hairs like the inner. 
There are no appendages whatever on any of the first five aba oni 
somites in any of the adult males examined. In young specimens, 15™™ 
or less in length, in which the sexual characters are not manifest, but 
which are possibly immature males, or more probably immature females, 
there are, however, on the second to the fifth somite, rudimentary, very 
