170 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
outermost terminal bristle of seventh joint of outer ramus more than 5 times as long as outer ramus. 
First basal joint of first pair of feet with inner marginal 
bristle; third joint of inner ramus of third and fourth 
pairs of feet each with a cluster of spines ; proximal 
piece of outer border of third joint of outer ramus in 
fourth pair about twice as long as distal piece. Fifth 
pair of feet as long as basal of fourth pair. 
Male: Separation between head and first thoracic 
segment more distinct than in female, whereas line of 
separation between fourth and fifth thoracic segments 
has disappeared. Abdomen consisting of 5 segments, 
of which third and fourth are shortest, the genital and 
anal segments longest. Furca smaller than in female, 
its bristles shorter and much less richly plumose. Feet 
much longer in proportion to trunk, especially to cephalo- 
thorax and posterior antennae ; maxillae and maxillipeds 
much shorter than in female. 
Coloration: Female very transparent, with orange 
or brick-red pigment not only in trunk hut also in 
appendages, especially in long bristles of anterior anten 
me and furca, and in broad plumes of latter, which have 
besides a metallic iridescence. These plumes can be 
spread, making Dana’s specific name a very appropriate 
one. Male transparent, with bright-red anterior anten- 
na', antenna], mandibular, and furcal bristles. 
Length: Female, 0.88 to 1.2 mm.; male, 1.04 mm. 
Numerous female specimens with much-damaged 
furcal plumes were taken in Gulf Stream July 25, 1899, 
at 8 p. m. It is a truly tropical species hitherto known 
only from the following localities : 12° N. 24° W. (Dana) 
Western Pacific to 175° W., between 3° S. and 19° N. 
from the surface to a depth of 1,000 (4,000?) meters 
(Giesbrecht) ; Canary Islands; Malta (Thompson). 
8. Calocalanus plumulosus Claus. 
Female: Abdomen 3-jointed; genital segment cu- 
boidal; furca and furcal bristles asymmetrical (leftlimb 
the larger of the two, fused with anal segment and fur- 
nished with an enormously long bristle). Terminal 
joint of anterior antennae twice as long as penultimate 
and twelfth joint. Outer ramus of posterior antennae 
five-sevenths as long as inner ramus ; outermost termi- 
nal bristle of seventh joint of outer ramus but little 
longer than the others. First basal joint of first pair 
of feet with an inner marginal bristle; third joint of 
inner ramus of third pair with 2 groups, of fourth pair 
with 1 group of spines; proximal piece of outer border 
of third joint of outer ramus in fourth pair 4 times as 
long as distal piece. Fifth pair of feet considerably 
longer than basal of fourth pair. 
Male: Unknown. 
Coloration: Female transparent, with orange or 
brick-red pigment scattered through the body and in 
antennal and furcal plumes. 
Length : 0.93 to 1.2 mm. 
Several female specimens of this interesting form 
were taken in the tow with the preceding species. 
In all specimens the greater portion of the huge furcal bristle had been broken off in the tow net, but 
Calocalanus plumulosus Claus; female, dorsal 
aspect. After Giesbrecht, with modifications. 
