26 



OSCAR SUND 



[REP. OF THE "MICHAEL SARS" NORTH 



^" d )nt ; 100 = 73 • 78 • 73 ■ 78 • 75 • 82 • 87 ■ 75; 

 3rd jnt. 



in S. pert. 82 • 96 • 82 • 89. 



There is no appreciable variation with the size of the 

 specimens. (3) the percentage of hairfringed edge on 

 the uropods, which can be determined rather easily is 

 very different from that in S. pectinatus. The following 

 values were found (no appreciable variation with size): 

 61-63-64-65-63-63-62-60-64-63; in S.pect: 74-75-78. 

 (4) the external maxilliped is very similar to that of the 



adult, but there are only 4 subjoints, the fourth being 

 later on divided into two. The armature is undeveloped 

 but the big spines are present and occupy similar positions 

 as in the adult, see fig. 47. Attention is drawn to the 

 fact that they are situated in pairs indicating a more 

 primitive stage of development of the one-sidedness of 

 the member, so pronounced in S. armatus, vigilax etc. 



Sergestes Henseni is a much larger species than S. 

 pectinatus, as the smallest males with petasma developed 

 are about 5 mm. (C), while in S. pectinatus the petasma 



Figs. 44—47. Sergestes Henseni.. 44) $ 7.5, st. 23, y 400, 6. joint of 3. mxp. ( 2 %). 45) </ 7, st. 51, y 300, petasma ( 3 °/i). 46) J 7, st. 51, 



y 300, process / of same ( 150 /i), 47) © 2, st. 64, y 300, 3. mxp. ( 50 /i). 



is present in males of only 3 mm. (C). Below is a table 

 recording the size of all the specimens taken during the 

 expedition. It should be compared with the corresponding 

 data for S. pectinatus. 



C (mm.) 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



Total 



Males 



Females 

 Young 



12 



15 



7 



2 

 4 



5 

 15 



8 

 13 



3 



1 



3 



4 



1 



18 

 41 

 36 







Sizes (C in mm.) 



Total 



• 



Depth 

 (metres) 





Below 5 



5 — 





Grand 

 total 





D 



N 



D | N 



D 



N 



D 



N 





0—100 



4 



8 



9 



3 



1 



7 



10 



10 



20 







150—300 



3 



9 



20 



1 



1 



34 



21 



35 



56 







600—1500 



3 



8 



1 







5 



10 



6 



10 



16 







Total 



10 



25 



30 



4 



7 



51 



37 



55 



92 







Grand total 



35^ 



34 



58 



92 

























From the table of bathymetrical distribution it ap- 

 pears that S. Henseni lives in depths of about 150 metres. 

 The data seem too scanty to allow of definite conclusions 



According to our present knowledge the area of 

 distribution is the same as that of S. pectinatus, with one 

 remarkable exception one specimen caught as far north 



being drawn as to diurnal migrations or differences in as st 88 ( a bout 45 ° N > 26 ° w )- 

 habitat of the young and adult. >) On vertical haul not incl. 



