42 



Pseudobranchial rami of second to fourth pairs of male pleopods nearly straight and 

 reaching a little beyond the middle the exopod (figs. ie and \f). Third pair of pleopods (fig. \f) 

 with the endopod somewhat longer than the exopod; penultimate joint of this endopod (fig. ig) 

 very elongated, with the outer terminal seta shorter than the joint and plumose, the inner 

 terminal seta rudimentary; last joint somewhat elongated, terminating in tvvo modified setae a 

 little longer than the joint and directed obliquely outwards; these setae are broad at the base 

 and seem to be flattened. Fourth pair of pleopods with the endopod only a little longer than 

 the exopod and with the distal setse modified (fig. i Ji) ; on the antepenultimate joint the outer 

 distal seta is feathered but somewhat short, while the inner is still shorter, very thin and naked ; 

 on the penultimate joint the two terminal setae are stiff, naked and nearly straight, and the 

 outer is much stronger than the inner and twice as long, being about as long as the sum of 

 the four distal joints; on the terminal joint the outer seta is still slightly longer and stronger 

 than the outer seta on the preceding joint, and about one-third as long again as the inner seta 

 of the terminal joint; exopod normal, with feathered terminal setae. 



Uropods (figs. i i and i /) more slender than in any preceding species ; exopod conspi- 

 cuously longer the endopod, with 10 — 13 spines occupying considerably more than the half of 

 the outer margin of the proximal joint, as the proximal spines are proportionately distant from 

 each other; its distal joint considerably more than half as long as the proximal, about two and 

 two-thirds to — sometimes in the male — three times as long as broad. Telson (fig. it) slightly 

 overreaching the articulation of the exopod, with the distal half a little more slender than in 

 S. cequiretnis and the margins of this part straight or sometimes in the male very feebly con- 

 cave ; the arrangement and length of the spines along the lateral margins and at the end 

 (fig. 1 k) quite as in S. cequiremis. 



Length 10 — ii mm. 



Remarks. — The male of this species is easily distinguished from all other forms of 

 the genus by the very curious antennal squama and the peculiar development of the distal part 

 of the endopod of third pair of pleopods. The female is readily distinguished from 5. cequiremis 

 by the conspicuous difference in the length of the rami of the uropods, and from S. inornata 

 and allied forms by the much longer and narrower second joint of the exopod of the uropods, 

 but it remains very uncertain whether it can be separated with any certainty from the female 

 of S. distinguenda, and it is not easy to separate from S. confoj'inalis, as may be seen in the 

 "remarks" on these species. 



22. Siriella distinguenda n. sp. PI. V, figs. 2a — 2e. 



Stat. 37. March 30/31. Sailus ketjil, Paternoster-islands. 2j ra. and less. Plankton, surface. 



1 specimen, cf. 

 Stat. 41. April 3. Lat. j° 25' S., long. 1 i/°5o'.5 E. 96 m. From 10 m. to surface. 2 male specimens. 



Besides I am apt to think that the female specimens captured at the following station 

 belong to this species. 



Stat. 125. July 18/19. Anchorage off Sawan, Siau-island. Plankton. 4 specimens, all 9- 



