its outer angle a very strong, acute, considerably curved, spiniform seta which is shaped about 

 as die outer seta or spine of the terminal joint hut is a good deal longér, reaching a little 

 beyond its end ; the long- seta is densely set with short, fine hairs about from the middle of its 

 front side to some distance from the end. The exopod have 5 distal spiniform seta-, all naked, 

 not differing very much in length and the two longest among them about as long as the outer 

 terminal seta of the endopod, but differing much from each other in shape and thickness: the 

 two terminal setse are very strong and thick at the base, the outer curved two times, the 

 inner considerably curved; the two setse placed at the inner angle of the penultimate joint are 

 somewhat slender and straight, while the seta at the outer angle of the same joint is a little 

 stronger and somewhat curved. 



The uropods (figs. 3^ and 3 i) scarcely as slender as in S. inornata ; the exopod distinctly 

 longer than the endopod, its proximal joint with 13 to 16 spines, of which frequently only the 

 two most proximal are rather distant from each other, and the distal joint not quite twice as 

 long as broad. Telson (figs. 3^, 3// and 3/è) nearly as in S. inornata, but the distal half of its 

 lateral margins is generally straight, more rarely slightly concave, so that the distal third of 

 the telson is proportionately a little broader than in 5. inornata (comp. fig. ^k with fig. 2/c, the 

 figures showing the distal part of the male telson in the two species) ; the lateral branches of the 

 two long, feathered terminal setse as in S. inornata extremely thin and far from easily visible. 



Length 1 o — 1 1 . 5 m . 



Remarks. — As already mentioned, the male is easily distinguished from that of 

 5. inornata by the number, shape and length of the modified distal setse of fourth pair of 

 pleopods; from S. plnmicauda m. it can be separated by the structure of the terminal feathered 

 setae on the telson. As to the females of S. media and S. inornata I refer to the "remarks" 

 on the latter species. 



Gronp 3. — End of telson with three small spines and a single pair of more lateral, 

 long spines. Proximal joint of the endopod of the uropods with more than half of its outer 

 margin furnished with spines, less than twice as long as the distal joint, which is from slightly 

 more than twice to about three times as long as broad. Proximal widened part of the telson 

 with three pairs of marginal spines ; spines along the distal third of the lateral margins essentially 

 as in group 2. Fourth pair of male pleopods with the endopod a little or somewhat longer 

 than the exopod and terminating in modified, spiniform setse, while the exopod is normal and 

 terminates in slender, feathered setae. (In one species even the endopod of the third pair of male 



Siriella flumicauda n. sp. 



Description of the Male. — Very closely allied to S. media, but easily distinguished by the aspect of the feathered setae 

 at the end of the telson and on the front side of the first pair of pleopods; in this form the lateral branches of these setae are strong, 

 instantly discernible with a feeble pocket lens, while in 5. media. S. inornata and the other species they are so thin that they can scarcely 

 be perceived without a considerably magnifying instrument. S. plumicauda otherwise agrees so closely with 5. media that a few remarks 

 may be sufficiënt. The modified spiniform seta; on the rami of fourth pair of pleopods essentially as in that form, but none of the terminal 

 setae of the exopod bent twice. Exopod of uropods with 16 marginal spines. Telson as to shape and spines nearly as in S. inornata, 

 consequently distally narrower than in S. media, and the lateral spines differ on the whole less in length, the smaller spines being longer 

 than usual. — Length of the single adult male 12 mm. 



Locality. — China Sea; lat. 2°o'S., long. io7°6'E. 1 adult male. Captain Andrka 1869. The Copenhagen Museum. 



