Entomostraca from the Arctic Seas. 347 
The thoracic feet are very slender. The outer branches 
are moderately elongated and three-jointed, while the inner 
branches, which in the second, third, and fourth pairs are con- 
siderably shorter than the outer ones, are two-jointed; figure 10 
on Plate V. represents the fourth pair. The preparation of 
the first pair was too imperfect for drawing. In the fifth 
pair (fig. 11) the basal joint is scarcely developed, but the 
secondary joint (or branch) is extremely elongated and slender, 
and bears a few apical setz, and one on the distal half of the 
outer margin; a slender process forming the base of a small 
seta extends from the outer aspect of the basal joint. 
The peculiar form of this Copepod, together with the slender 
thoracic feet, and especially the extremely long and slender 
secondary branches of the fifth pair, distinguish it from any 
other species of Cletodes known to us. 
Cletodes abyssicola, T. & A. Scott (sp.n.). (Pl. V. figs. 1-8.) 
Description of the Female.—Length from the forehead to 
the end of the caudal furca about ‘9 mm. (5, of an inch). 
Viewed from above the body is nearly cylindrical, and the 
posterior margins of the various segments are fringed with 
minute bristles ; the cephalic segment is armed with a strong 
and backward-curved median dorsal spine, and a small spine 
also arises from the median dorsal aspect of the last abdomi- 
nal segment, as shown in the drawing (fig. 1; figs. a and } 
show the anterior and posterior dorsal spine as seen in profile). 
The caudal furea are long and slender, being nearly equal to 
half the entire length of the body. 
The antennules are moderately elongated and seven-jointed ; 
the second and third joints are subequal, and are together 
about as long as the entire length of the remaining four joints, 
which are also subequal. The proportional lengths of the 
joints are shown approximately by the formula :— 
Number of the joints...... te Zi on ae eV Oe ae 
Lengths of the joints...... 12-2) eh FIs Rea 
The antennules are sparingly setiferous, and the third joint 
bears a moderately long asthetask (fig. 2). 
The secondary branches of the antenne are almost obsolete, 
being each reduced to a single seta, which springs from the 
end of the second joint (fig. 3). 
The mandibles are moderately stout and provided with a 
comparatively broad masticatory part; the palp is small and 
composed of two joints, the second of which is very minute, 
both joints bear a few terminal sete (fig. 4). 
