FREE-SWIMMING COPEPODS OF THE WOODS HOLE REGION. 
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blade in some species slightly, in others considerably, reduced; second basal joint shortened, inner 
ramus inserted nearer end of joints; appendages of inner border of maxilla} and of anterior maxilliped 
not generally reduced ; modification of posterior maxillipeds like that of Calanus. 
3. Eucalanus attenuatus Dana. 
Female: Only one segment between genital and anal segments ; front triangular, indented on 
either side, tapering decidedly; genital segment longer than broad; furca and second terminal bristle 
asymmetrical; first and second joints of outer ramus of posterior antennae separated; inner ramus 
1^ times as long as second joint of inner ramus and four times as long as broad; second basal of 
mandibles with 2 inner marginal bristles; tip of inner ramus 
not reaching distal edge of second basal joint by more than 
length of ramus; first joint of inner ramus without bristles, 
second joint with 4 bristles; second inner lobe of maxillae 
present; third inner lobe with 4 bristles, second basal joint 
with 5 bristles. Posterior maxilliped lias first joint of inner 
ramus with 3 bristles, third joint with 4 bristles. 
Male: Pronounced secondary sexual characters; right 
fifth foot present, left much shorter than the fourth foot. 
Coloration : Transparent, with a variable amount of red 
pigment in body and often in some of basal joints of anterior 
antennae and proximal terminal joints of appendages; terminal 
plumes of anterior antennae colorless, or red, with iridescence. 
Length of female, 4.2 to 4.85 mm. ; of male, 3.1 to 
3.25 mm. 
A single female specimen taken in the Gulf Stream tow 
July 25, 1899. The plumes at the tip of the anterior antennae 
are much damaged, but there can be no doubt of the specific 
identity. In life the translucent body contains more or less 
bright-red pigment, irregularly and often asymmetrically dis- 
tributed. In my specimen the antennal plumes are colorless, 
at least in part, but in specimens studied by Giesbrecht they 
were sometimes bright orange with blue or violet iridescence. 
4. Eucalanus monachus Giesbrecht. 
Female: Only one segment between genital and anal seg- 
ments; genital segment somewhat broader than long; asym- 
metry of furca slight; first and second joints of outer ramus 
of posterior antennae fused ; first joint of inner ramus shorter 
than second and about twice as long as broad ; second basal 
joint of mandibles with 3 inner marginal bristles; inner ramus 
almost reaching dorsal margins of second basal joint ; first, joint 
of inner ramus with 2, second with 4 bristles; second inner 
lobe of maxilla lacking, third inner lobe with 3 bristles, second 
basal with 4 bristles ; first and second joints of the inner ramus 
of posterior maxilliped each with 3 bristles. 
Male: Less pronounced secondary sexual characters; right fifth foot wanting. 
Length of male, 2.13 to 2.35 mm. ; of female, 2.2 mm. 
A single male specimen taken in Gulf Stream July 25, 1899. Hitherto this species has only been 
taken at Gibraltar (Giesbrecht, 1888). 
5. Mecynocera clausii Thompson: female; 
dorsal aspect. 
MECYNOCERA J. C. Thompson. 
Furca symmetrical, articulating with anal segment; mandible shorter than maxilla and less than 
half as long as fourth pair ot feet; its structure similar to that of Calanus, but inner ramus is nearly 
as long as second basal and twice as long as outer ramus; inner ramus of posterior maxillipeds at 
least as long as first or second basal; first pair of feet with 3-jointed outer and 1-jointed inner 
ramus; fifth pair of feet present, on either side 5-jointed. 
Male: Unknown. 
