33 



Male considerably more slender than female, with the lateral corners 

 of last segment of metasome far less produced. Urosome very narrow, with 

 the last segment much shortened; caudal rami generally spread to each side. 

 Anterior antennse rather slender, with the number of articulations considerably 

 reduced. Last pair of legs simple, without any trace of an inner ramus, left leg 

 very slender, right leg rudimentary, scarcely more than y 3 as long as the left, and 

 3-articulate, last joint conically produced at the tip. 



Colour. Body pellucid, with a faint yellowish tinge, and in female varie- 

 gated with scattered light red patches, partly confluent into transverse bands; 

 intestine translucent with a dark ochraceous hue; ovaries purple-coloured. 



Length of adult female 2.65 mm., of male 2.20 rnm. 



Remarks.- This is unquestionably the form described by Biady as Pseudo- 

 calanus armatus, Boeck. Since this identification of Brady has turned out to be 

 wrong, another specific name should of course have been assigned to the present 

 species, the more so as the name armatus has been used for two other forms 

 belonging to the present family, viz., ^Etideus armatus and Chiridius armatus. I 

 therefore think that the name Undinopsis Bradyi, long ago proposed by the present 

 author for this form, ought to be peferred to that of Bradyidius armatus used 

 by most other authors. 



Occurrence. I have met with this form in several places on the Nor- 

 wegian coast, from the Christiania Fjord to Vard0. It is only found close to the 

 ground in depths ranging from 20 to 40 fathoms, muddy bottom, and accordingly 

 cannot, as a rule, be taken with the ordinary surface -net, but only by the aid of 

 the dredge. In order to get specimens in uninjured condition, the dredge must, 

 however, be of a very light kind and so constructed, that it only sweeps the 

 bottom, without being filled up with mud. By the aid of such a dredge I have 

 succeeded in obtaining this form rather abundantly in some places, and have not 

 infrequently had the opportunity of examining it in the living state. Like most other 

 Calanoids, it moves in two different manners, now proceeding quite slowly by rapid 

 vibrations of the posterior antennce and the mandibular palps, now making abrupt 

 bounds by energetic strokes of the powerful natatory legs. When kept for obser- 

 vation in a glass bottle with a small quantity of mud, it is always found to keep 

 close to the bottom, moving about along the mud in a horizontal direction. 

 By far the greater number of specimens obtained are of the female sex. Male 

 specimens are extremely rare, and seem only to occur at certain seasons. 

 . British Isles (Brady, Scott), Greenland (Vanhoffen). 



