TYPHLOSCOLECIDAE. , 151 



The neurocirri in the posterior somites are lanceolate and uniformly doeidedly 

 smaller than the notoeirri; in the anterior somites they become much narrower 

 and less foliaceous, appearing somewhat tentacular in form though still thinner 

 in one diameter. (Plate 25, fig. 9, 10). 



The composite setae have the appendages very long and fine at the tip, 

 the base being nearly as broad as the shaft, though relatively narrower than in 

 angelini. There seems normally to be a single stout seta in each parapodium. 

 Most of these are broken off and it was impossible to be wholly certain as to 

 the presence of an appendage. 



Locality. Between California and the Hawaiian Islands, nearer to the 

 former: Sta. 3681 (lat. 28° 23' N., long. 126' 57' W.). 100 fms. to surface. Sur- 

 face temp. 66° F. 27 August, 1899. One specimen. 



This form seems to approach R. angelini (Kinberg), described originally 

 from the Pacific off the Coast of China. It is, however, conspicuously different 

 in the form of the anterior notoeirri in particular, these remaining narrow and 

 becoming small instead of becoming conspicuously broader and broadly rounded. 

 The appendages of the composite setae appear relatively much longer and more 

 slender. Omitting consideration of the coarse setae, the present species may 

 be distinguished from R. henseni Apstein by its narrower notoeirri, and from 

 R. gracilis Costa { = R. nasuta (Greeff)) by its much smaller prostomial tubercle. 



TYPHLOSCOLECIDAE. 



These are all small and exclusively pelagic forms in which the body is 

 nearly colorless and transparent. The length of the body is mostly between 

 2.5 mm. and 15 mm., rarely as much as 32 mm. The number of somites is 

 small, being from sixteen to fifty. 



Prostomium fused with the peristomium to form a single division or "head" 

 which is drawn out into a conical or rostrate form and bears a single median 

 process or tentacle, which may be set off by a distinct articulation or not, and a 

 pair, or two, of lateral foliaceous cirri. Dorsal and ventral surfaces often 

 much extended into lappet-like processes or expansions, which may bear conspicu- 

 ous ciUary processes. 



In most, nuchal organs have not been detected, but in some they are strongly 

 developed. 



The parapodia are uniramous and small, or rudimentary, and bear each 

 a single aciculum and two, or but few, simple curving setae. The cirri are 



