30 U.S. NATIONAL MUSEUM BULLETIN 259 



lobes of lower lip, and by the defined distoposterior lobes of bases of 

 pereopods 5-7. Further distinguished from S. mundus, with which it 

 occurs sympatrically, by the shallow excavation in apical margin of 

 the telson. Largest male, 6.00 mm; largest female, 6.75 mm. 



Antenna 1 about 50 percent as long as body and about twice the 

 length of antenna 2; primary flagellum of 15 to 17 segments. An- 

 tenna 2, flagellum with up to 7 segments. Mandibular palp segment 3 

 comparatively broad, with about 7 long setae; segment 2 with 7 setae. 

 Maxilla 1, mner plate with 7 apical, plumose setae. Maxilla 2, inner 

 plate with 9 long, obliquely placed, plumose setae, Maxilliped, 

 outer plate reaching beyond apex of 1st palpal segment. Lower lip 

 with very small to rudimentary inner lobes. 



Gnathopod 1: propod palmar margin less oblique than in two 

 previously described species, slightly concave, armed with a double 

 row of about 8 spine teeth; posterior angle with 3 large, unequal spines 

 on outside, 4 smaller spines on inside; posterior margin without setae; 

 lateral setae few in number, singly inserted; dactyl claw long. 

 Gnathopod 2: propod palmar margin straight to slightly concave, 

 armed with a double row of 8 or 9 spine teeth; posterior angle with 1 

 large spine on outside, about 3 small spines on inside; posterior margin 

 with 3 sets of setae; lateral setae mostly smgly inserted; claw of 

 dactyl long. Coxal plates of pereopods 2 and 3 with 5 to 7 marginal 

 setae each; that of pereopod 4 with 10 or 11 setae. Pereopod 7 about 

 equal in length to pereopod 6 and 20 to 25 percent longer than pereopod 

 5. Bases of pereopods 5-7 nearly as broad distally as proximally, 

 distoposterior lobes developed but not much produced ventrally. 

 Dactyls of pereopods 6 and 7 nearly 50 percent as long as correspond- 

 ing propods; dactyl of pereopod 5 not as long proportionately. Sternal 

 gills absent on 1st pleonite of male but present in female; 7th pereopod 

 coxal gills absent in both sexes; all other gills present. 



Abdominal side plates: posterior margins convex, with 1 or 2 

 setae each; posterior corners distinct, subacute; ventral margin of 

 plate 2 with 3 spines, that of plate 3 with 5 spines. Pleopod 1, 

 inner ramus about equal in length to peduncle. Uropod 1 with up 

 to 34 spines; outer ramus about 3/4 as long as inner ramus, a little 

 more than one-half the length of peduncle. Uropod 2 with up to 

 20 spines; outer ramus about 80 percent as long as inner ramus, 

 about 70 percent as long as peduncle. Uropod 3: ramus about 1/3 

 as long as peduncle, armed apically with 3 spines in male and 4 spines 

 in female; peduncle armed with 1 distolateral spinule. Telson about 

 40 percent longer than broad, apical margin with a shallow excavation 

 and armed on each lobe with about 4 spines in males and about 

 6 spines in females. 



