20 



OSCAR SUND 



[REP. OF THE "MICHAEL SARS" NORTH 



between those edges. This feature together with others 

 in a large male from st. 64 is shown in fig. 33. 



Both the uropods and the scaphocerite show a reti- 

 cular or cellular pattern, also found in S. mollis. The 

 integument is soft as in that species and supraocular and 

 hepatic spines are absent. 



The branchiae are feeble compared with those of 

 5. robustus, though not in such a state of reduction as 

 found in 6". mollis (see Smith 1887). Relative length of 

 four posterior branchiae 6 — 2 — 4 — 3, the second branchia 

 above trl. 3 being very small and onesided. 



The form of the secondary antennular flagellum in 

 the male is seen in fig. 32. 



S. tropicus is one of the larger Sergestes, one female 

 and one male measuring about 70 mm. (C = 21). It 

 was found only in the southern part of the area examined, 

 in all 18 specimens having been taken. It seems to be 

 a deep-water species, as all the large specimens were 

 taken at a depth of 1000 metres or more, even though 

 most of the hauls were made during the night. 



Colour orange, except mouthparts which are reddish- 

 brown. The dark stomach can be seen through the body. 

 The eyes are large and black, the tubercle is of the 

 same colour as the stalk. 



Table of catches, 



St. 



Gear 



m. w. 



Number 



Sex, size 



29 



y 



2000 



2 



2 19, cT 18 



45 



y 



2000 



1 



2 13 



49 



4 In 



3000 



4 



d" 21, 19, 12, $ 12 



51 



V2 sn 



700 



1 



© 7, (def.) 



n 



V2 sn 



1000 



1 



?9 



* 



y 



3000 



1 



?9 



w 



4 In 



4000 



1 



2 10 



52 



3 In 



1200 



1 



2 10 



53 



3 In 



2600 



4 



ci" 19, 18, 18, ? 11 



56 



3 In 



3000 



1 



cf 18 



64 



3 In 



3000 



1 



(7 21 



8 



11 





18 



9d\ 8 2, 1 © 



Sergestes mollis Smith. 



5. mollis, Smith 1884. 



S. mollis, Smith 1887. 



5. japonicus, Hansen 1896. 



5. japonicus, Hansen 1903(2). 



I have been somewhat in doubt as to what name 

 should be adopted for the numerous "Michael Sars" 

 specimens which agree in every particular with Smith's 

 descriptions and figures, but have decided not to follow 

 Hansen in regarding S. mollis as a synonym of S. ja- 



ponicus Bate (Bate 1881, 1888). The evidence given by 

 Hansen in support of his view seems too scanty. He has 

 compared the three 30 years old and mutilated "Chal- 

 lenger" specimens with Smith's description, and found 

 no difference. He says: — "It should be specially mentioned 

 that an examination of the branchiae showed the most 

 complete agreement with Smith's description and drawing". 

 Still, he has not seen any Atlantic specimens, or he would 

 have noticed that the form of the rostrum differs greatly 

 from that of the specimen figured by Bate (1888, pi. 70), 

 and until it can be shown that this difference is due to 

 inaccurate drawing by Bate, it is safest to regard S. mollis 

 and S. japonicus as distinct species. 



Fig. 34. Sergestes mollis ,d" 17, st. 81, 3 In 3000. Petasma ( 25 /i). 



The petasma (fig. 34) is remarkable for the rudi- 

 mentary stage of the small hooks and tubercles on the 

 processes. It is possible, though not very probable, that 

 even the largest of our male specimens are not fully 

 developed. 



S. mollis is undoubtedly a deep-sea species, as will 

 be seen from the following table of bathymetrical distri- 

 bution (3 ind. from vertical hauls not consid.): — 





Nr 



of 



Sizes (C. in mm.) 







*« 



Depth 

 (metres) 



hauls 



4—10 



11—17 



18—26 





C 





D 



N 



D 



N 



D 



N 



D 



N 



D 



N 



t-4 



O 



350— 800 



6 



5 



13 



14 



5 



2 







18 



16 



34 



1000—1300 



4 



5 



12 



25 



3 



11 



2 



1 



18 



37 



55 



1500—2100 



5 



7 





16 



16 



3 



7 



2 



22 



20 



43 



Total 



15 



17 



25 



55 



24 



16 



9 



3 



58 



74 



132 



Grand total 



32 



80 



40 



12 



132 





