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



PINEIDES AND STENOPIDES 



23 



Sergestes armatus Kroyer 



5. armatus Kroyer 1855 (mastigopus) 

 5. armatus Hansen 1896 ( — „— ) 



This species has hitherto been known only from its 

 mastigopus stage, but during the "Michael Sars" expedi- 

 tion many adults were captured, which 1 shall briefly 

 describe. 



40 



39 



41 



figs. 39—41. Sergestes armatus. 39) $ 14, St. 23, y 400, rostrum 



>( 5 /i). 40) ? 14, St. 23, y 400, end of 3. mxp. ( 10 A). 41) d" 10, St. 51, 



y 300, petasma ( 3 %). 



Rostrum adscendent, its outer third tapering to an 

 .acute point (see fig. 39). Supraocular and hepatic spines 

 present, the latter situated upon a marked keel running 

 from the base of the antenna and disappearing behind 

 -the spine. The branchiocardial keel and furrow are also 

 distinct and reach the hinder edge of the carapace. 



In the antennular peduncles, the aggregate length of 

 which is about' 85 % of the length of the carpace, the 

 first and the second joints are nearly equal, the third 

 being about one-third longer than either. 



The very long third maxillipeds have the sixth joint 

 divided into four subjoints, the relative lengths of which 



are as 21:30:16:33. All four subjoints carry strong 

 spines arranged as shown in fig. 40. In all the specimens 

 the distal subjoint is strongly curved. 



The outer uropods are fringed with setae along 2 / 3 — 3 U 

 of their external edge, and a spine is present only in 

 some of the young specimens. 



The petasma (fig. 41) recalls to some extent that of 

 S. vigilax. 



As far as can be judged form material preserved in 

 formaline pigment is absent, except in the stomach, which 

 is purplish. 



5. armatus is a large species, compared with the 

 others in Hansen's group II, as will be seen from this table: 



Size (C in mm.) 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



14 



Total 



Males 









1 



1 





1 



1 











4 



Females 









1 



3 



3 



1 



4 



1 





1 



1 



15 



Young 



5 



4 



2 





















11 



The nearest relative of 5. armatus Kr. is 5. diapon- 

 tius Bate H. J. H (= S. penerlnki Bate H. J. H.), but is 

 distinguished from it by the form of the antennular 

 peduncles and the relative length of the hairfringed por- 

 tion of the outer uropods. 



5. armatus has been identified with certainty only in 

 the Atlantic. Bate's specimens from the Pacific and from 

 Australian waters, are not, according to Hansen (1903), 

 correctly determined. 



Regarding the bathymetrical distribution not much is 

 known, and the "Michael Sars" material is too scanty to 

 allow of any definite conclusions being drawn. (See table 

 of catches). 



Table of catches. 



St. 



Gear 



m. w. 



Number 



Sex, size 





23 



y 



400 



1 



? 14 





45 



y 



300 



5 



? 10, 10, 8, 8, 7 





» 



4 In 



3000 



1 



? 10, 





51 



1 sn 







2 



©3, 3 







1 sn 



200 



1 



d"6 





u 



y 



300 



2 



? 10, d" 10 





53 



y 



300 



2 



? 9, 7 





n 



y 



600 



1 



?7 





64 



1 sn 



100 



3 



© 3Vi, 3, 3 





„ 



1 sn 



200 



2 



©4 l /2, 4 







y 



300 



3 



© 4, 4, 3 







y 



1000 



2 



?8,.d«7 







y 



2000 



1 



?6 





67 



1 sn 



50 



1 



$11 





, 



3 A sn 



600 



1 



©4Vi 





n 



y 



1200 



2 



2 13(L = 36), d"9 (L = 



= 31) 



6 



17 





30 



15 $, 4 d", 11 © 



