48. Metridia longa (Lubbock). 



(PI. LXXV & LXXVI). 



Calanm longus, Lubbock. On some Arctic Species of Calanid.-i-. Ann. nat. hist,., ser. 2, 



Vol. 14, p. 127, PI. 5, fig. 10. 



Syn: Metridia armata, Boeck. 



Specific Characters. Female. Body exceedingly slender, with the anterior 

 division, seen dorsally, oblong in form, greatest width but slightly exceeding 1 / s 

 of the length, and occurring about in the middle, anterior extremity somewhat 

 contracted and narrowly rounded at the tip, posterior gradually attenuated. 

 Cephalosome much shorter than metasome, and having the dorsal face quite 

 evenly vaulted, rostral projection somewhat prominent. Lateral parts of last 

 segment of metasome rounded off at the tip. Urosome very slender, exceeding 

 in length the metasome, genital segment about the length of the other 2 com- 

 bined, and only very slightly dilated in front. Caudal rami comparatively large, 

 fully as long as the anal segment, and somewhat widening distally, apical seta3 

 rather short, the innermost but one the longest, seta of the outer edge occurring 

 at about 2 / 3 f the length of the caudal ramus. Anterior antenna;, when reflexed, 

 reaching about to the middle of the genital segment, 1st, 2nd, 4th, 5th, 6th 

 and 10th joints each produced at the end anteriorly to a small dentiform 

 projection. Last pair of legs distinctly 4-articulate, last joint the smallest, 

 and carrying 3 slender ciliated setae, the innermost the longest, and extending 

 obliquely inwards. 



Male rather smaller than female and still more slender, with the urosome 

 very narrow and elongated. Left anterior antennae (more rarely the light) 

 geniculate, with the middle section only slightly tumefied. Last pair of legs 

 exhibiting the structure characteristic of the genus, terminal joint of both legs 

 oblong in form, with the distal part somewhat contracted, spiniform process of 

 antepenultimate joint of right leg rather elongated, slightly sigmoid and finely 

 denticulated on one side distally. 



Colour. Body in both sexes highly pellucid, almost hyaline, sometimes 

 with a slight brimstone-coloured shade on the anterior part of the cephalosome. 



Length of adult female reaching to 4.30 mm., of male to 3.70 mm. 



Remarks. This form was described, though rather imperfectly, by Lubbock 

 in the year 1854 as Calanus longus. The same form was subsequently found 

 off the Norwegian coast by Boeck, who describes it as Metridia armata, the 

 specific name being probably derived from the dentiform projections which some 

 of the articulations of the anterior antennae form in front. It may be regarded 



