218 BULLETIN 68, UNITED STATES NATIONAL MUSEUM. 



the sutures. Aperture ovate; posterior angle acute; outer lip thin; 

 columella short, slender, curved and feebly revolute, provided with 

 a fold at its insertion. 



The type (Cat. no. 206927, U.S.N.M.) was dredged at U. S. Bureau 

 of Fisheries station 2794, off Panama Bay, in 62 fathoms, sand, 

 temperature 59°. 5. It has five j)ost-nuclear whorls and measures: 

 Length 2.7 mm., diameter 1 mm. 



Subgenus AMAUBA Mbller. 

 Amaura Moller, Index Moll. Groenlandica, 1842, p. 7. 



Very large, usually inflated Odostomias, the sculpture of which con- 

 sists of very fine lines of growth and still finer wavy closely placed 

 spiral striations. 



Type. — Amaura Candida Moller. 



KEY TO THE SPECIES OP THE SUBGENUS AMAURA. 



Shell umbilicated. 



Shell very large, adult more than 10 mm. long. 



Shell very elongate-ovate lastra, p. 219. 



Shell broadly ovate. kennerleyi, p. 219. 



Shell less than 10 mm. long. 

 Shell ovate. 



Summit of the whorls concavely shouldered elsa, p. 220. 



Summit of the whorls narrowly flatly shouldered beringi, p. 220. 



Shell very elongate-ovate. 

 Umbilicus rather wide. 



Summit of the whorls with a faint shoulder satura, p. 221. 



Summit of the whorls with a strongly tabulated 



shoulder farallonensis, p. 221. 



Umbilicus very narrow. 



Summit of the whorls ap pressed sillana, p. 222. 



Summit of the whorls shouldered. 



Shoulder concave t.alpa, p. 222. 



Shoulder narrowly tabulated. 



WTiorls strongly contracted at the suture. . . .krausei, p. 223. 

 Whorls not strongly contracted at the suture. 



Adult shell 7.8 mm. long orcia, p. 223. 



Adult shell 6.1 mm. long gouldi, p. 224. 



Shell not umbilicated. 



Shell very large, adult more than 12 mm. long arctica, p. 224. 



Shell less than 10 mm. long. 

 Shell elongate-ovate. 



Summit of the whorls appressed avellana, p. 225. 



Summit of the whorls not appressed. 

 Columella free for its entire length. 



Shell finely spirally Urate moratora, p. 225. 



Shell not finely spirally Urate. 



Shell large and robust, adult 9.3 mm. long pesa, p. 226. 



Shell of medium size, not robust, adult 7.5 mm. long.. no(a, p. 226. 

 Columella free only in its anterior half iliuliukensis, p. 227. 



