21 



Male rather unlike the female, and of considerably smaller size. Cephalo- 

 some slightly dilated in front, but scarcely carinated dorsally. Urosome very 

 narrow, with the anal segment shorter than in female, and somewhat dilated 

 distally; caudal rami very mobile, finely ciliated inside, and having the terminal 

 edge somewhat produced in the middle. Anterior antennae with the number of 

 articulations considerably reduced, a fusion having taken place, not only of the 2 

 proximal ones, but also of the 8th to 12th and of the 20th and 21st articulations. 

 Last pair of legs rather asymmetrical, left leg much the longer, with the 2nd and 

 3rd joints slightly dilated distally, terminal joint very small and tipped with a 

 slender spinule; right leg not nearly reaching to the end of the penultimate joint 

 of left, and terminating in a straight, subulate point. 



Colour. Body in both sexes very pellucid, though generally with a faint 

 reddish yellow tinge; oral area, as a rule, tinged with crimson, and the genital 

 protuberance of the female with light green. 



Length of adult female 1.40 mm., of male 1.10 mm. 



Remarks. This form was first recorded by Boeck from the Norwegian 

 coast under the name of Clausia dongata, and was subsequently rediscovered in 

 the bay of Kiel, by Dr. Giesbrect, who described it as Lucullus acuspes. It is 

 easily recognized from the other Norwegian Ampliascandria by its slender and 

 elongated tail, a character which has, indeed, given rise to the specific name pro- 

 posed by Boeck. 



Occurrence. I have met with this form very frequently along the whole 

 Norwegian coast from the Christiania Fjord to Vads0, both in the open sea and 

 close to the shores, where it is occasionally left in tidal pools. It often occurs 

 at the very surface of the water; but it sometimes also seems to descend to 

 greater depths, though on the whole it may be regarded as a true pelagic form. 

 Specimens are not infrequently found carrying a small number of ova enclosed in 

 a thin-skinned, rounded ovisac, which, as usual, is appended to the ventral side 

 of the genital segment; but this ovisac is so very fragile, that at the slightest 

 touch it may become detached. Male specimens are much more scarce than 

 females and, when alive, may be easily recognizable even to the naked eye by 

 their somewhat different jerky movements. 



Distribution. Unlike Paracalanus partus, this Calanoid has a pronoun- 

 cedly northern range, the most southern place where it has been observed being 

 the northern coast of France (Canu). On the other hand, it is distributed 

 throughout the whole northern Ocean from Baffin's Bay in the west to the New 

 Siberian Isles in the east. It also inhabits the Baltic together with other forms 

 of evidently arctic origin. 



