15 



segment is seen to terminate in well defïned spines. Thè abdomen is four-jointed, symmetrical, 

 and equal to one-third of the length of the ccphalothorax. The genital segment is longer than 

 broad, and is nearly eqnal to the combined lengths of the second and third segments. The 

 second segment is about half the length of the genital segment. The third segment is equal 

 to two-thirds of the length of the second. The fourth segment is about half as long as the third. 

 The furcal joints are short and slightly longer than broad but rather longer than the last 

 abdominal segment. 



The antennules are twenty-five-jointed and extend beyond the end of the abdomen by 

 at least four joints. 



The antennae, mandibles, and maxillae are nearly as in Calanus. 



The first maxillipedes are furnished with distinct curved spines on the third, fourth, and 

 fifth lobes, that on the fifth being quite conspicuous. The apical portion of the first maxillipedes 

 bears a number of spines, which are densely clothed with short fine hairs. 



The second maxillipedes have a general resemblance to those of Calanus but the apical 

 portion is only indistinctly five-jointed. 



The five pairs of feet are bi-ramose and each branch is composed of three joints. The 

 second joint of the basiopodite of the first pair of feet is furnished with a simple plumose seta 

 on the anterior surface. The last joint of the exopodites of the second, third, and fourth feet, 

 bear three marginal spines as in Megacalaims princeps. The fifth pair of feet is of a similar 

 structure to the fourth, but the last joint of the exopodites has only two marginal spines. 



The only record for Bradycalanus typicus in the 'Siboga' material is two mature females 

 taken in a Hensen net vertical haul at Station 148 from a depth of 1000 metres to the surface. 

 It is evident that Megacalanus princeps and Bradycalanus typicus, are deep water Calanoids, 

 as they were only found in the vertical hauls taken between 1000 and 1536 metres. 



It is probable, that the present species is specifically distinct from Calanus princeps Brady, 

 as I think it is very unlikely that Bradv in his description would have overlooked the terminal 

 spines on the last thoracic segment, had they been present in his species. 



I am unable to decide whether Bradycalanus typicus is identical with Sars Megacalanus 

 princeps or not, as nothing beyond the record of its occurrence has yet appeared. Farran also 

 unfortunately, has not given illustrations of the Calanoid he recognises to be identical with Calanus 

 princeps Brady, and Megacalanus princeps Sars. Farran (1908) regards Wolfenden's Hctero- 

 calauus medius to be generically and specifically identical with Megacalanus princeps (Brady). 

 In that case Brady's Calanoid cannot be a Megacalanus at all, as Wolfenden distinctly states 

 that there is no hook on the second joint of the basiopodite of the first feet, and it cannot 

 be the present species, as Heterocalanus medius is described as having a prominent dorsal crest, 

 which is quite absent in Bradycalanus typicus. 



I have lately had an opportunity of examining a specimen of a large Calanoid with a 

 dorsal crest, from the deep water of the Faröe Channel. It agreed in every way with Wolfendex's 

 Heterocalanus medius, but differs from Bradycalanus typicus by the possession of a dorsal crest, 

 the terminations of the last thoracic segment are rounded, and the apical spines of the first 

 maxillipedes are more densely clothed with fine hairs. 



