ATLANT. DEEP-SEA EXPED. 1910 VOL. Ill] 



PENEIDES AND STENOPIDES 



13 



From the vertical distribution as evidenced by the 

 "Michael Sars" catches it appears that S. robustus is a 

 deep-sea prawn, only the younger stages occurring in 

 the upper strata, but never at the surface. There is a 

 marked difference in the colouring of the adult and the 

 young, the latter being almost transparent, only the pur- 

 plish blue stomach shining through the carapace. The ex- 

 ceedingly beautiful colouring of the adult (scarlet lake with 

 crimson spots, golden feather-bristles and blue reflections) 

 is well described by Kemp (1910). 



Table of catches. (Hauls made during neight marked *) 



St. 



Gear 



m. w. 



Number 



Sex, size 



23* 



1 sn 



200 



5 



2 11, 10, 9, 9, ©7 





* 







y 



400 



2 



d" 10, ? 8 





$ 



T 



(1215) 



1 



59 





34* 



y 



400 



1 



59 





* 



l k sn 



600 



2 



? 9, 9 





35 



4 sn 



2400-0 



3 



<? 11, $ 11, 10 







V2 sn 



4200 



1 



5 10 





42* 



y 



900 



4 



2 11, 11, 10, 10 





53* 



y 



300 



2 



d" 10, ? 8 





* 



y 



600 



2 



©6, 6 





n 



V2 sn 



2100 



1 



©7 





;i: 

 n 



3 In 



2600 



4 



tf 18, 17, ©7, 7 





56* 



1 sn 



100 



1 



©7 





* 



1 sn 



200 



1 



©6 





* 



y 



300 



5 



© 7, 7, 7, 7, 7 





* 



y 



1000 



3 



© 7, 7, 7, 





.* 



y 



2000 



2 



2 10, ©6 





M " : " 



3 In 



3000 



13 



2 10, 10, 10, 9, 9, 8, 8, © 7, 7, 7, 7 



6,6 



58* 



y 



300 



3 



2 10. © 8, 7 





€2 



1 sn 



200 



2 



d"9, 2 11 





* 



y 



1000 



2 



cT9, ©6 





* 



y 



2000 



2 



©7, 5 





* 



3 In 



3000 



2 



d" 19, 11 





63 



4 sn 



1350-450 



1 



©8 





64 



y 



2000 



9 



2 17, 10, 10, 10, 10, 10, ©9, 7, 



7 





3 k sn 



2500 



2 



d"8. 2 8 





n 



3 In 



3000 



5 



cT21, 2 8, 8, 8, ©7 





66 



y 



1500 



3 



d" 9, 7, 2 8 





67 



y 



1200 



14 



d" 8, © 7, 7. 6, 6, 6, 6, 5, 5, 5, 5, 5, 



5,5 



81 



y 



2000 



1 



d<9 





87 



Z U sn 



1500 



1 



2 8 





» 



y 



2000 



2 



2 8, ©7 





88 



y 



1000 



3 



d" 9, 8, © 7 







3 A sn 



1500 



1 



c?9 







y 



2000 



1 



2 10 





90 



y 



1000 



4 



2 9, 9, © 7, 7 





92* 



y 



300 



2 



d*9, 2 9 





% ''■' 



3 A sn 



600 



2 



2 8, © 6, 





■■!■■ 



y 



1000 



1 



28 





98 



y 



1000 



18 



©8a 7, 9a 6, 1 a 5 mm. 





„ 



3 /i sn 



1450 



1 



©6 





n 



3 In 



1500 



10 



d" 22, © 8, 8, 7, 7, 7, 7, 7, 7, 7 





101 



3 /i sn 



1500 



2 



©6, 5 







y 



2000 



2 



©6, 6 





102 



y 



1000 



2 



©7, 6 





20 



45 



151 



d" 21, 2 46, ©84 



Larva. 



4 and 7 mm. (C = 1-7 — 2-5 mm.) and they agree perfectly 

 with Bates' (1888), Ortmann's (1893) and Hansen's (1903) 

 descriptions of 5". dissimilis, which Hansen later (1908) 

 cancelled as being the young of S. robustus 1 ). 



A study of the telson in these larvae and in the sub- 

 adult 5. robustus and its nearest allies makes Hansen's 

 statement probable, though some transitional stages (C = 

 3-4 mm.) are needed to make the series complete. Fig. 

 2 and 3, pi. I, are photographs of the head and tail-fan 

 of a specimen 4-7 mm. long (C = 2-1), and in textfig. 14 

 outline drawings of telson of the same specimen and of 



14 15 



S. robustus (juv.). Fig. 14. Tip of telson in 4 young specimens. 

 Size (C) inscribed in each drawing. The two smallest from st. 64 y 300, 

 the others from s. 98, y 1000. Fig. 15. Abdomen of © 1.7 in fig. 14. 



a smaller one (but subadult specimens of S. robustus) are 

 given. I will be noted that the larvae and the subadults 

 possess the same number of lateral spines. In the smallest 

 of the subadults (C = 5) the tip is still cleft while in the 

 largest it has become simple. In one specimen with forked 

 tip, not figured, a single tip was observed ready to take 

 its place after moulting. 



In the smallest larvae (C = 1-5 — 1-7) there were 

 also spines on the 2nd and 3rd abdominal somites, in 

 the very smallest (1-5) even on the first, while the spec- 

 imens described by Bate (L = 10 mm.), by Ortmann 

 (10—12 mm.) by Hansen (9-5 mm.) and the others taken 



At the stations 51, 52, 53 and 64 a number of 

 mastigopus stages were taken which I believe may be 

 referred to Sergestes robustus. Their length is between 



l ) H. I. Hansen writes (1908): "It appears now that 5. dissi- 

 milis is the mastigopus stage of S. robustus, so that intermediate 

 stages have been described as S. incertus H. I. H. and as "the sub- 

 adult stage of S. mediterraneus H. I. H." I presume that "S. in- 

 certus" in the passage cited is a misquotation for S. inermis. 



