254 PROCEEDINGS OF THE ACADEMY OF [April, 



being about three times the diameter of the region of the body from 

 which they spring. 



Setae begin on III as a pair of minute tufts arising from an elevated 

 position just beneath the gills. The tufts on IV are also small and 

 placed nearly as high. On succeeding somites the setae become larger 

 and more numerous and the tufts gradually assume a low station on 

 the sides of the body as the abdomen is approached. They continue 

 to XIX. 



Uncinial tori begin on VI, or the fourth setigerous somite. Through- 

 out the thoracic region they are low, but freely projecting, compressed 

 folds which arise immediately ventral and slightly posterior to the 

 setae tufts and end ventrally in a freely hanging lobe or process. On 

 abdominal segments the notopodia are distinctly separated from the 

 neuropodia and project as small papillae from the dorsal angles of the 

 body. The neuropodia are small, compressed lappets constricted at 

 the base and bearing the' uncini along the free margin; apparently they 

 lack cirri. 



Setae are all of one kind, slender, tapered and narrowly winged on 

 both sides of the free portion nearly to the very acute tip. The uncini 

 form a close single rank in which they are quite numerous (108 on X). 

 From dorsal to ventral end of each series they decrease in length. 

 They (fig. 52) are roughly triangular with a nearly square but sometimes 

 projecting upper ligament process, above which the tooth-bearing 

 margin rises but slightly. The inferior process varies in form, but is 

 usually more or less incurved. Those of the type specimen almost 

 constantly bear four long, slender, acute, overlapping teeth, the ven- 

 tralmost of which is the stoutest, the two middle the longest and the 

 upper the most slender. On the cotype a fifth smaller and sometimes 

 minute tooth exists at the upper end of nearly all uncini (fig. 52a). 

 Abdominal uncini (fig. 53) have the same form, but are much fewer in 

 number. 



This species is founded on two much macerated specimens, of which 

 the larger and type is 30 mm. long and filled with large ova. The 

 smaller example is 16 mm. long. 



A nearly complete tube is 65 mm. long. Its basal third is soft, 

 thin-walled and membranous. Beyond this the walls gradually 

 thicken by the accumulation of silty material until they attain a 

 diameter of about 5 mm. This entire region of the tube is supported 

 and protected by siliceous sponge spicules, the ends of which project 

 in all directions and produce a very firm and bristling structure. 



