404 THE ANNELIDA POLYCHAETA. 



in width, not so noticeably widening toward one end. Rounded at the ends. 



Body densely clothed with slender filaments forming a thick coat, as in 

 the other species. 



The neuropodial setae are pale brown, being a little darker than in hythin- 

 cola. Whereas in the latter species the neuropodial setae are apparently of 

 nearly equal stoutness throughout the length of the body, in the present species 

 they become very much more slender caudad, the long anterior ones being 

 very much coarser than the most posterior ones. Most setae in the type are 

 broken off near the base; the longest anterior one, which is distally incomplete, is 

 in the present condition 44 mm. long, so that originally it must have approached 

 the body in length. Notopodials very fine and short, pale. 



Length, 55 mm.; greatest width, 22 mm. 



Locality. Galapagos: off Hood Island, 12 miles S. E. of Ripple Point. 

 Sta. 4649 (lat. 1° 35' S., long. 89° 30' W.). Depth 633 fms. Bottom of light 

 grey Globigerina ooze. Bottom temp. 39.5° F. 10 November, 1904. 



Stern ASPiDAE. 



These are highly specialized polychaetes, of very distinctive appearance. 

 The body is short, consisting in superficial appearance of 19-22 somites, but 

 morphologically, as judged by the number of fasciae of setae in the posterior 

 region, composed of thirty-one somites {S. scutata Rietsch, Ann. sci. nat., 1882, 

 13, p. 7; Vijdevsky, Densk. Akad. wissen. Wien, 1882, 43, p. 35). Of these, 

 fifteen lie in front of the ventral shield, a characteristic double horny, but not 

 truly chitinous (Goodrich, Quart, journ. micr. sci., 1898, 40, p. 239) plate or 

 shield, from the edges of which radiate fasciae of long setae on the ventral sur- 

 face at the posterior end of the body. The first seven somites in the state of 

 repose are retractile. The integument in general is covered with numerous 

 fine, hair-hke papillae, which are typically more numerous and coarse caudad of 

 the seventh somite. The integument caudad of this somite is commonly also 

 longitudinally furrowed, or striate. To the surface adhere numerous, chiefly 

 silicious, particles, much as in the Flabelligeridae. 



The prostomium is a very small rounded lobe just over, or in front of, the 

 mouth. It bears neither eyes nor appendages. 



Peristomium, or first somite, without setae. 



The anus opens on a papilla above the ventral shield. 



On each side of and above the anal papilla are two dense bundles of long, 



