68 U.S. NATIONAL MUSEUM BULLETIN 2 59 



distinguished from S. hayi, to which it also closely related, by less 

 spinose telson in males, less spinose 1st iiropod in females, less spinose 

 2nd uropod in both sexes, and by straighter posterior margins of 

 bases of pereopods 5-7. Largest males, 13.50 mm; largest females, 

 13.00 mm. 



Male. — Antenna 1 up to 50 percent as long as body, 20 to 25 

 percent longer than antenna 2 in larger males; primary flagellum 

 with 21 to 25 segments. Antenna 2 relatively long; flagellum with 

 8 to 12 segments, penultimate segment not exceptionally large or 

 arcuate. Palpal segment 3 of mandible with 6 to 10 long setae, 

 segment 2 with 5 to 8 setae. Maxilla 1, inner plate with 4 to 6 apical, 

 plumose setae. Maxilla 2, inner plate with 2 to 4 long, obliquely 

 placed, plumose setae. Maxilliped, inner plate with 3 or 4 (usually 

 3) thick apical spines. Inner lobes of lower lip comparatively broad. 



Gnathopod 1: propod palmar margin oblique, relatively straight 

 to slightly concave, armed with a double row of 8 or 9 spine teeth; 

 posterior angle with 1 large spine and 4 or 5 smaller spines on outside, 

 5 small spines on inside; posterior margin short, with 3 sets of setae; 

 lateral setae few in number. Gnathopod 2: propod palmar margin 

 comparatively straight to slightly convex, armed with a double row 

 of about 8 spine teeth; posterior angle with 1 large spine and 4 or 5 

 smaller spines on outside, 5 or 6 small spines on inside; posterior 

 margin long, with 6 or 7 sets of setae; lateral setae in transverse rows, 

 doubly and singly inserted; coxal plate about as broad as long, with 

 7 marginal setae. Coxal plates of pereopods 3 and 4 broader than 

 long, with 8 or 9 marginal setae each. Pereopods 5-7 generally 

 corresponding to those described for S. tenuis and as shown in figiu-e 

 14. Gill arrangement complete except that sternal gills are occa- 

 sionally absent on 1st pleonite of the male. 



Abdominal side plates: posterior margins convex, with 2 to 4 setae 

 each; posterior corners rounded, indistinct; ventral margins with 2 

 or 3 spines each. Pleopod 1, inner ramus nearly twice as long as 

 peduncle. Uropod 1: outer ramus about equal in length to inner 

 ramus, only about 55 to 60 percent as long as peduncle; rami with 

 about 11 spines each; peduncle with up to 14 spines. Uropod 2: 

 outer ramus 75 to 80 percent as long as inner ranius, about 50 percent 

 as long as peduncle, armed with about 6 spines; inner ramus with 10 

 spines; peduncle with 5 spines. Uropod 3, ramus up to 50 percent 

 as long as peduncle and armed with 4 to 6 apical spines. Telson not 

 quite as long as broad; armed apically with 11 or 12 unequal spines, 

 the outermost usually deflected laterally from the midline and armed 

 with 1 or 2 inner distal tines. 



Female. ^ — Differing in a few minor details as follows: Antenna 1 

 between 50 and 60 percent longer than antenna 2; primary flagellum 



