2IO DISCOVERY REPORTS 



observe the quite independent origin of the two appendages. The nauplius figured by 

 Claus was attributed by him to Calanella {Eucalanus), but according to Giesbrecht it 

 was wrongly named, the nauplius of Eucalanus being like that of Rhincalanus . Similar 

 elongated nauplii are said by Giesbrecht to be found among Pontellidae. 



With (1915, p. 46) has described copepodid IV and V of R. nasutus, and has figured 

 leg 5 of the male in these two stages. Schmaus and Lehnhofer (1927) have dealt with 

 the later copepodid stages of all three species of Rhincalanus and particularly with the 

 development of leg 5 of the male. They showed also that there are two forms of 

 R. cornutus (forma typica and forma atlantica) distinguished by the form of leg 5, and 

 that similar differences can be seen in copepodid stages IV and V. 



THE NAUPLIUS STAGES 



Five stages only are recognizable in the material, but it is almost certain that the 

 youngest is actually stage II. 



Stage II, R. cornutus. Length 0-45-0-47 mm. (Fig. 1.) 



C 



Fig. 1. 



D 



Fig. 2. 



Fig. 



Rhincalanus nasutus, nauplius stages. 



Stage II. Fig. 2. A, antennule, stage II; B, antennule, stage III; C, furcal region, stage III; 



D, furcal region, stage IV. 



