506 PROCEEDINGS OF THE NATIONAL MUSEUM vol.99 



rows of minute pigment spots. The palpi, to be seen by lifting the 

 tentacles, are about as long as the latter but taper from thicker bases 

 to slender tips. 



Branchiae occur on all segments except the last few, where tori 

 are long and slender; they are largest in the anterior half of the body 

 and diminish thereafter so as to be absent on about the last ten 

 segments. 



Anterior thoracic segments have neuropodia only. The first has 

 a pair of inconspicuous fascicles of very fine slender delicate setae, 

 distally strewn with minute slender hairs. In the second segment 

 the setae are larger and have a serrated limbate region at the free 

 end. They resemble setae of neuropodia farther back. 



Parathoracic segments are biramous. Their notopodia have single 

 transverse rows of paleae alternating with slender acicular spines; 

 they number about four pairs in the first, six or seven in the second, 

 and seven or eight in the third segment. The paleae are distally broad 

 and end in long, slender serrations (fig. 40, &) . 



In the abdomen, notopodial tori have uncini in single transverse 

 series ; the uncini are very minute though numerous ( 50 to 100 or more 

 in a row, where best developed). Each is a pectinate plaque with five 

 (fig. 40, h) or six teeth in a single row. The cauda is smooth and 

 cylindrical ; it ends in a terminal anus. 



The tubes are massed to form concreted clumps ; they are sufficiently 

 friable to be broken when dropped from a table. Individual tubes 

 measure about 2.3 mm. in outside diameter and 1 mm. or less within. 

 The individual sand gi-ains are uniformly small, largely colorless 

 quartz particles. 



S. floridensis stephensoni is nearly related to the stem species from 

 southwestern Florida. In both, the inner opercular paleae are ser- 

 rated, interpeduncular spines occur at the dorsal end of the operculum, 

 and the middle paleae alternate long and short. In the stem species, 

 however, the outer opercular paleae are distally much longer and more 

 strongly serrated, the peduncle is blotched rather than striped, the 

 over- all size is somewhat greater (14 or 15 mm.), and the body is more 

 robust than in the subspecies. 



Others from the Western Hemisphere with serrated inner opercular 

 paleae are distinguished in table 1. There remain S. pectinafa Fauvel 

 (^1928, p. 163) from India, with its variety intermedia Fauvel (1932, 

 p. 210) from India, and S. ceinentarimn Fauvel (1932, p. 210) from 

 India {not Moore, 1906, p. 248, from the northeast Pacific) . The third 

 has outer opercular paleae with a long, smooth, slender spike and 

 middle paleae all short. The first has greatly prolonged, strongly 

 serrated outer paleae, and its variety, intermedia^ has middle paleae 



