158 STALK-EYED CRUSTACEA. 
Nematocarcinus agassizii Fax. 
Plate XLII. 
Bull. Mus. Comp. Zodl., XXIV. 204, 1893. 
The rostrum is one fifth longer than the rest of the carapace (in some small 
specimens only equal to the rest of the carapace), slender, nearly horizontal 
for the basal two fifths of its length, the remaining portion gently upturned 
and ending in a very acute point; its upper margin is continued backward 
in the form of a carina, which becomes obsolete on the hinder part of the 
gastric region; this carina is pectinate, or armed with close-set, forward- 
pointing teeth on the anterior part of the gastric region, and the teeth are 
continued on the upper margin of the rostrum through one third or two 
fifths of its length, the distal third or three fifths of the rostrum being 
entirely free from teeth above; the lower edge of the rostrum is ciliated 
above the eyes and armed with three (rarely four) teeth, separated by wide 
intervals, on the distal half. 
The third abdominal segment is somewhat prolonged posteriorly over the 
next segment, but the hind margin is rounded off and does not form a promi- 
nent tooth. The telson is tipped with three pairs of spines, the intermediate 
pair the longest; there are, besides, about six pairs of small spines on the. 
dorsal side of the telson. 
The flagella of both the antennules and antenne are prodigiously de- 
veloped, the antennule being nearly twice, the antenna more than twice the 
length of the whole body including the rostrum; excepting the proximal part 
of the organ, the annuli of the antennal flagellum are enlarged at the distal 
end, giving a beaded appearance to the flagellum ; the antennal scale reaches 
rather more than half-way to the end of the rostrum ; it is truncate at the 
distal end and armed externally with an apical spine. 
The legs have the characteristic shape and proportions of the genus. The 
dactyli of the third and fourth pair are slender, acute, somewhat curved, and 
invested with a pencil of long hairs. The dactyli of the fifth pair are stouter 
but very short, and hidden in the tuft of hairs which arises from the distal end 
of the propodite. 
The outer blade of the swimmeret slightly surpasses the telson. It is 
fringed with long hairs along the internal and distal margin, and furnished 
with a minute tooth and a movably articulated spine on the external border 
