NANS SIMPLEX. 125 



Between the Galapagos and Paumotu Islands: Sta. 4736 (lat. 19° S., long. 

 125° 05' W.). 300 fms. to surface. Surface temp. 81° F. 23 January, 1905. 

 One specimen. 



Nans gen. nov.^ 



Body short, tapered both cephalad and caudad, moderately depressed. 

 Number of somites small. 



Two pairs of eyes present. Tentacles two pairs, no unpaired one and no 

 nuchal papilla. 



Somites all distinct from each other and from the prostomium. 



Normal parapodia biacicular, bearing both notocirrus and neurocirrus, 

 these filiform. 



Setae all simple, but of two types, a stout ventral crochet form, and a longer, 

 thin and flat form borne by the notopodial branch. Only the first type detected 

 on somite I in the type-species. 



Character of proboscis undetermined. 



Genotype. — N. simplex, sp. nov. 



This genus is at once distinguished in wholly lacking composite setae, 

 the simple setae, however, being of two sharply distinct types. In other feat- 

 ures, as well, the genus does not conform to any of the subfamilies into which 

 Bergstrom in his recent monograph (Zool. bidrag., 1914, 3, p. 117) divides the 

 family. From the Eteoninae, which it approaches, for example, in the number 

 and arrangement of the tentacular cirri, it differs in having the notocirrus of 

 the first normal segment strongly developed instead of reduced. The Lugiinae 

 have similarly two pairs of tentacular cirri, but these pertain to two somites 

 instead of to a single one. It becomes necessary, therefore, in this system to 

 place Nans in a new subfamily, the Nantinae. The relationships of the subfami- 

 lies are indicated in the general key (p. 99). 



Nans simplex, sp. nov.^ 



Plate 18, fig. 7, 8; Plate 19, fig. 1-4. 



The body is colorless and transparent. 



Widest near the middle of length and conspicuously narrowed both cepha- 



1 nans, a swimmer. 



2 simplex, simple. 



