88 
is not detailed enough to make its identity sure.” The same 
remark will apply to the present specimens. With Faxon’s 
description they agree so closely, that it would be rash to base 
a specific separation on the one or two minute differences which 
have to be noticed. 
Faxon very carefully describes the carapace, including 
“rostrum cristiform, short, laterally compressed, directed 
obliquely upward, subquadrate in outline, the anterior margin 
produced to form a short point near the middle.” Neither in 
text nor figure does he indicate the slight distal excavation of 
the upper margin, terminated by a small tooth, found in both 
the female specimens with which we are here concerned. He 
says that “the second, third, and more especially the fourth 
abdominal somites are lightly sulcate in the median dorsal line,” 
which is true of our specimens, but they have the sulcation in 
a slight degree also on the first segment. In his figure of the 
uropods Faxon leaves the whole outer margin devoid of sete, 
whereas in our specimens this margin, as in the nearest allied 
species, is bare above the lateral tooth but densely setose below 
it. The omission of these sete from the figure is not noticed in 
the text, and may be due to an accidental oversight. In all 
other respects the carapace and pleon, the sub-spherical eyes, 
the maxillipeds and limbs in their details and relative lengths 
accurately agree with Faxon’s account. 
A small specimen taken by the Challenger Expedition be- 
tween Valparaiso and Juan Fernandez, from a depth of 200 
fathoms, was named S. nasidentatus by Spence Bate, evidently 
from the peculiarity that it had the “rostrum produced to a 
sharp point, and armed on the upper surface with a distinct 
tooth, a little anterior to the frontal margin.” Hansen deter- 
mines this to be a Mastigopus, belonging to the same group as 
Sergestus arcticus, Kroyer. It is not impossible that this may 
be the Mastigopus form of S. bisulcatus. 
Colour, according to Wood-Mason, “in the fresh state deep: 
crimson lake.” South African specimens red, fading to orange. 
Wood-Mason gives the “length of male from tip of rostrum 
to apex of telson 60mm., of female 63mm.” Faxon says, 
“Length 65 mm., carapace 21mm.” The female specimen 
here figured measured from tip to apex 76mm., the carapace 
in the medio-dorsal line being 24 mm. 
Locality —Cape Point, E. by N., 29 miles ; depth, 250 to 300 
fathoms ; bottom, green sand and mud. 
