1896. ] OF THE GENUS SERGESTES. 961 
the one margin furnished with extremely short spines or almost 
naked, while the other margin of the sixth joint and at least of the 
distal half of the fifth joint is armed with rather numerous spines, 
some of which are very long and rather robust. The differences in 
the armature, especially of the sixth joint, yield very good characters 
for the species. (The distal part of the fifth joint is most frequently 
cut off by a secondary articulation.) The eves are middle-sized, 
the supraocular and hepatic spines well developed. In the antenn. 
ped. the first joint is very little longer to somewhat shorter than 
the third joint, which is slender and obviously longer than the 
second. On the third joint of trl." and trl.* the processes represented 
by Kroyer in S. edwardsi (tab. iv. fig. 9 f and 9 g) are well 
developed. The branchial formula as in S. atlanticus, M.-Edw. 
(see above) ; the branchiz above the trunk-legs are very long, above 
trl.’ one branchia and a lamella; trl.* 2 branchie, the first of which 
is about as longas the preceding, the second somewhat shorter and 
only half as broad, but yet very well developed. The exterior 
margin of the ext. br. of urp. without any spine or tooth at the 
proximal end of the ciliated part. 
S. edwardsi, Kr.—Kroyer in his representation (p. 246, tab. iv. 
fig. 9, a-k) mentions a variety with longer rostrum, but this 
belongs to another species, viz. S. penerinki, Bate, H. J. H. The 
species is easily distinguished from all the other species by the 
character given in my tabular view: that the ext. pr. of urp. has 
the exterior margin ciliated along its whole length—and besides 
by the following features in the structure of mxp.* The sixth 
joint of this pair is divided into 4 subjoints about equal in length, 
and each of the 2 distal subjoints is rather or very distinctly divided 
into 2 subjoints, thus in all 6 subjoints; the joint ends with 2 spines 
of equal or different length, but at least the one is very long; next 
its interior margin is furnished with 35-38 spines of very different 
lengths (and the apical spine on the first, second, and fourth of the 
6 subjoints is exceedingly long); besides a very long spine is present 
on the same three subjoints on the one side near the exterior margin. 
The fifth jomt of mxp.’ also presents some characters, which, 
however, are omitted. The rostrum is shorter than in the other 
species of the group, laterally compressed, and seen from the side 
more or less plainly forming an oblique triangle——Length 14- 
21:5 mm. 
I have seen specimens from the Atlantic northward to lat. 20° N. 
(the larvee to lat. 23° 31' N.), from the Indian Ocean, and passing 
towards the Pacific to Dyilolo Isl. (c. lat. 1° N., long. 127° 5’ E.). 
The three, or perhaps four, next species are easily separated from 
S. edwardsi, Kr., by several characters. On the ext. br. of urp. at 
least c. § of the exterior margin is naked. In map. the siath joint 
is divided into but 4 subjoints very unequal in length, the third 
being but half as long as the second; the joint ends with but one 
spine, which is very long, and the interior margin of the joint is 
armed with but 15-25 spines, and uo spine exists on the side of 
any of the subjoints near the exterior margin. 
62* 
ws 
