36 



Description. — Closely allied to 5. vul garis. Carapace in the male slightly produced 

 in front (fig. 30), leaving the area between the insertion of the eyes uncovered, the front 

 margin being feebly angularly bent, but the tip itself a little produced, acute; the female has 

 a considerably produced, triangular, acute frontal plate, which is moderately narrow, a little 

 longer than broad and a little longer than in S. quadrispinosa. Eyes large, conspicuously larger 

 than in 5. vulgaris, dark with a reddish tint or nearly black. Antennular peduncle in the male 

 moderately thick. Antennal squama in the female (fig. 3 c) somewhat less than three times, in 

 the male (fig. 3 ö) three times, as long as broad ; terminal lobe at least more than half as 

 broad again as long, frequently twice as broad as long. Gnathopods (fig. ^d) and especially 

 the thoracic legs (fig. 3 c) rather robust. Male pleopods and pseudobranchial rami (fig. 3/") as 

 in the preceding species. 



Uropoda subsimilar in both sexes (figs. i,g and 32), moderately slender; exopod slightly 

 longer than the endopod, with generally 3 to 5, rarely 6 — 7, marginal spines ; distal joint of 

 the exopod slightly more than half as long as the proximal joint and not fully twice as long 

 as broad. Telson (figs. 3^" and 3/z) subsimilar in both sexes, reaching conspicuously beyond the 

 articulation of the exopod, and as to shape and spines essentially as in S. vulgaris, but the 

 lateral spines, which as to distance are arranged regularly along half of the lateral margins, 

 increase in length regularly only along a little less than one-fourth of the margins, and the 

 most distal pair of these spines are frequently more than two-thirds as long as the long pair 

 of terminal spines. 



Length of the male 7 — 7.5 m., of the female 6 — 6.5 m. 



Remarks. — The large difference between the sexes as to the frontal plate is very 

 interesting. This feature and the short terminal lobe of the antennal squama afford the best 

 characters, by which S. affiuis is distinguished from 6". vulgaris. 



Group 2. 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 much more than half of its outer 

 margin furnished with spines, and at least about twice as long as the distal joint, which is at 

 most twice 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 of the telson closely set, but irregular 

 as to length, as several long spines are found, and between each two of these some, or near 

 the end only two or one, smaller or small spines are inserted. Both rami of fourth pair of male 

 pleopods terminating in very modified setee. Pseudobranchial rami of second to fourth pairs of 

 male pleopods spirally twisted. 



18. Siriella inornata n. sp. PI. IV, figs. 2a — 2k. 



Stat. 37. March 30/31. Sailus ketjil, Paternoster-islands. 27 m. and less. Plankton, surface. 

 9 specimens, cf and Q. 



Stat. 40. April 2. Anchorage off Pulu Kawassang, Paternoster-islands. 12 m. Townet. 2 spe- 

 cimens, both 9- 



Stat. 41. April 3. Lat. 7 25' S., long. 1 17 50.5 E. 96 m. Plankton, surface. 9 specimens, cT and 9- 



Stat. 99. June 28/29/30. Lat. 6° 7.5 N., long. I20°26' E. Anchorage off North-Ubian. 16 — 23 m. 

 Townet. 4 specimens, all 9- 



