COPEPODS OF THE WOODS HOLE KEGION" 



121 



Distribution. — Arctic Ocean (Lubbock, Mrazek) ; Greenland 

 (Biichholz) ; Spitzbergen (Lilljeborg) ; northern Atlantic (Cleve) ; 

 Scottish seas (T. Scott) ; Faroe Channel (Norman) ; Baffin Bay 

 (Hansen) ; Polar Basin (Giesbrecht) ; coast of Norway (Sars) ; 

 Greenland (Damas and Koefoed) ; Alaska (Willey) ; Gulf of Maine 

 (Bigelow). 



Color. — Body colorless and transparent, sometimes whitish, with a 

 small dull red spot between the bases of the first antennae in front 

 of the eye; the latter a bright carmine-red (Rathbun). 



Fevicde. — Metasome nearly three 

 times as long as wide, its posterior 

 corners rounded; genital segment as 

 long as the abdomen and protruded 

 ventrally; caudal rami nearly three 

 times as long as wide and somewhat 

 broadened distally ; fifth legs distinctly 

 4-segmented, the end segment much 

 smaller than any of the others, with 

 2 unequal apical setae and a much 

 longer one on the inner margin, all 

 plumose; second and third segments 

 each with an outer spine. Total 

 length, '^^.5 mm. 



Male. — Body more slender and elon- 

 gated than in the female ; left an- 

 tenna geniculate usually, sometimes 

 the right one; each fifth leg 5-seg- 

 mented, the right leg longer than the 

 left, its end segment strongly nar- 

 rowed distally, the spiniform process 

 on the third segment denticulate; sec- 

 ond segment of left leg with an inner fringe of hairs, end segment 

 strongly tapered distally, penultimate segment with a short inner 

 spine. Total length, 3.5-4 mm. 



Remarks. — This species is nearly as abundant as the preceding 

 and is well distributed throughout the area, which fact, together 

 with its large size, gives it considerable economic importance. Sars, 

 in the reference given above, said : " When disturbed, it sends out 

 from its body a bright flash of a bluish color. This flash is so 

 intense that even by full daylight it can easily be seen." Such a 

 statement would seem to indicate that longa., as van Breemen has 

 mentioned in his Nordisches Plankton (1908) with reference to 

 lucens, is luminescent, and contributes to the phosphorescence that 

 is so prevalent in the oceanic portions of the present area. 



Figure 80. — Metridia longa: a. Fe- 

 male, dorsal (after Sars) ; &, 

 female, fifth legs ; c, male, fifth 

 legs 



