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



PENEIDES AND STENOPIDES 



15 



The branchiae are as in S. robustus, differing only 

 in the relative size of the posterior branchia above the 

 third pereiopod, this branchia being only two thirds as 

 long as the anterior, while in S. robustus it is nearly as 

 large. The posterior branchia above the fourth pereiopod 

 is V 5 as l° n g as xne preceding one. 



The first joint of the antennular peduncles is slightly 

 shorter than the second and the third together. The 

 second is about one fourth longer than the third, which 

 is not much more than two times longer than broad. 



The form of the scaphocerite and the outer uropod 

 may be seen from fig. 17. On both appendages is no- 

 ticed even in the smallest specimens a row of peculiar 

 patches which I believe to be luminous organs, their po- 

 sition being analogous to that of the light organs of 

 S. glorlosus Stebbing and S. Challenged Hansen. In the 

 young specimens the patches are fewer in number, while 

 in the young of S. robustus no patches are visible till 

 the animal has reached a size of a full-grown S. splendens. 



The colouring of newly preserved formaline spec- 

 imens consists of an intense scarlet on the fore part of the 

 back, fading gradually into the transparent abdomen and 

 legs. In the alcoholic specimens the colour is persistent 

 only along the grooves of the carpace. 



The nearest relative of S. splendens is undoubtedly 

 S. Gardlnerl Kemp (Kemp 1913) which is proved by the 

 petasma in these species, (see fig. 18) that of S. splendens 

 carrying however only one process (e in the figure) were 

 S. Gardlnerl has two. Other points of distinction may 

 be derived from the relative length of the branchiae, and 

 of the joints of the antennular stalk; the presence in 

 S. splendens of patches believed to be luminous organs, etc. 



Also from the species described by Stebbing (1908) 

 as S. blsulcatus S. splendens is easily distinguished by 

 the presence of the lastnamed character and by its size 

 (C. never exceeding 12 mm. in the 111 specimens, while 

 Stebbings specimen measured 24, the total length being 

 76 mm). From S. glorlosus and S. blsulcatus Wood Mason 

 our species is distinguished by its characteristic petasma 

 which resembles only that of S. Gardlnerl as stated above. 





Table of bathymetrical distribution. 1 ) 







Depth 

 (m.) 



Hauls 



Size (C in mm.) 



Total 



< 7 



7—9 



> 9 





D 



N 



D 



N 



D 



N 



D 



N 



D 



N 



50—100 



101—250 



> 250 



2 

 1 

 5 



5 

 5 

 6 



3 

 25 



10 

 1 



1 

 3 



10 



40 



3 



4 



3 

 5 

 3 



3 



1 



32 



13 

 55 



7 



Total 



24 



'AS 



11 



4 



53 



4 



11 



36 



75 



Horizontally S. splendens is apparently limited to the 

 southern part of the area explored. The accompanying 

 table of batymetrical distribution seems to indicate that 

 the species avoids the upper waterlayers during the day, 

 but ascends during the night, though it has not been 

 taken at the very surface of the sea. 



Table of catches. 



St. 



Gear 



m.w 



Number 



Sex, size 



29 



y 



400 



1 



?9 



42 



y 



300 



1 



?8 



45 



1 sn 



100 



1 



c?7 



„ 



1 sn 



200 



6 



? 7, 7, a" 7, 7, 7, 7 



» 



y 



300 



50 



?: la 10, 2a 8, 16 a 7, 1 a6and4 a 5 mm. 

 d" : 1 a 10, 2 a 8, 18 a 7 and 5 a 6 mm. 



„ 



y 



2000 



1 



2 10 



B 



4 In 



3000 



1 



29 



49 



4 In 



3000 



4 



2 10, 7, d» 10, 6 



51 



1 sn 



200 



1 



d"io 



„ 



y 



300 



2 



cf 10, 9 



„ 



V2 sn 



1000 



1 



d"6 



52 



V2 sn 



100 



2 



c/6, ?5 



53 



1 sn 



100 



4 



2 10, d" 9, 9, 8 



„ 



y 



300 



1 



d"10 



„ 



y 



600 



2 



2 9. 7 



» 



3 In 



2600 



1 



d"8 



56 



1 sn 



200 



1 



2 11 



n 



y 



300 



1 



2 10 



62 



y 



2000 



1 



2 10 



64 



1 sn 



100 



1 



©4 



n 



y 



2000 



3 



cT 10, © 4, 4 



66 



3 A sn 



1000 



1 



?s 



67 



3 In 



2000 



2 



d*8(L = 29), 2 12(L = 39) 



n 



y 



1200 



22 



(/:4 a 6 and 4 a 5 mm, 2 : 4a 6 and 

 8 a 5 mm, 02 a 4 mm. 



12 



24 





111 





l ) Heavy figures denote the number of specimens taken during 

 the night. 



Larvae. 



At stations 64 and 67 some larvae were taken which 

 I believe may be referred to S. splendens. They resemble 

 this species very much in the form of the cephalic append- 

 ages, even the rudiment of the ocular tubercle being 

 visible as a protrusion from the nerve (see fig. 20, which 

 also shows the form of uropod typical of S. splendens). 

 It is true that an ocular tubercle is present in many 

 species of Sergestes, but none of these species were 

 taken in the same area with the larvae in question. 



An examination of the telson points also to S. splendens. 

 Fig. 21 shows the outlines of the telson in the three 

 larvae, and in a nearly adult S. splendens. It will be 

 noted that the three pairs of dorsolateral spines found in 

 the smallest larva;, have disappeared in the two larger 

 larvae, but the form of the tip convinces one of the 

 specific identity of the three larvae, neither could any 

 other differences be found than those connected with 



