56 



curved in the middle, number of articulations considerably reduced. Last pair of" 

 legs very slender, reaching beyond the tip of the urosome, terminal joint of right 

 leg bayonet-shaped, that of left leg transformed to a thin oblong lamella. 



Colour. Body in both sexes highly pellucid, and almost without any 

 pigment; natatory legs, however, generally tinged with yellow. 



Length of adult female 1.40 mm., of male about the same. 



Remarks. I have been in some doubt about the identification of this 

 form, chiefly because Prof. Brady describes the 5th pair of legs in the female as 

 3-articulate. I think, however, that this must be due to a mistake, and that in 

 all probability the legs figured do not belong to a female specimen, but more 

 properly to an immature male. Otherwise the figures given agree pretty well 

 with the present form, the peculiar bayonet-shaped appearance of the terminal 

 joint of the right last leg in the adult male being exactly alike in the 2 forms. 



Occurrence. I have met with this form occasionally along the greater 

 part of the Norwegian coast, from the Christiania Fjord northwards at least to 

 the Lofoten Islands. It has also recently been found, though rather sparingly, 

 in some of the plankton-samples taken in the open sea during the cruise of the 

 "Michael Sars" in 1900. In its habits this Calanoid is a true pelagic form, often 

 occurring close to the surface of the sea. 



Distribution. North Atlantic Ocean (Brady), Gulf of Guinea (Scott), 

 Indian Ocean (Giesbrecht). 



Section 2. 



Isokerandria. 



This new section is established to comprise a number of Calanoids 

 which are distinguished from those belonging to the 2 sections recorded by Dr. 

 Giesbrecht (Araphascandria and Heterarthrandria) by the fact, that the anterior 

 antennae do not exhibit any conspicuous difference in the two sexes, and that the 

 oral parts, as a rule, are also of much the same appearance in the male and the 

 female. The hitherto known forms belonging to this section had previously been 

 referred partly to the Scolecithricidue, partly to the Pseudocalanidce, and partly to 



