184 BULLETIN 6S, UNITED STATES NATIONAL MUSEUM. 



and equally spaced spiral keels between the sutures, the first of which 

 is at the summit. The spaces separating the keels are strongly in- 

 cised, a little wider than the keels and crossed by numerous, slender 

 retractive axial riblets. Periphery of the last whorl marked by a 

 keel. Base somewhat protracted, well rounded, minutely umbili- 

 cated, marked by seven spiral cords which grow successively weaker 

 from the periphery to the umbilicus; spaces between the cords 

 marked like those on the spire. Aperture large; posterior angle 

 acute; outer lip thin, showing the external sculpture wdthin; colu- 

 mella long, slender, somewhat curved, very strongly reflected, pro- 

 vided with a strong fold at its insertion; parietal wall covered by a 

 thin callus. 



The type (Cat. no. 4102 U. S. N. M.) comes from Cape St. Lucas, 

 Lower California. It has four post-nuclear whorls and measures: 

 Length 2.3 mm., diameter 0.7 mm. 



Subgenus MENESTHO Moller. 



Meneslho Moller, Ind. MolL Greenl., 1842, p. 10. +Odetta de Folin, Fonds de 

 la Mer, 1870, p. 314. Type, Odctta elegans de P^olin. -\- Jaminea de Folin, 

 Constit. Method, de la Fam. Chemnitiziidse, 1885, p. 15. Type, Jaminea 

 bilirata de Folin; not Jaminea Brown, 1827. -\-Jaminina de Folin, Zool. 

 Record, vol. 22, 1885, p. 94. Type. Jaminea bUirata de Folin. 



Shell not unibilicated, marked by moderately well developed and 

 usually equally spaced spiral cords; axial sculpture reduced to mere 

 lines of growth w^hich frequently appear as i^eri/ slender raised tlireads 

 in the grooves between the cords. 



Type. — Turbo alhulus Fabricius. 



key to the species op the subgenus MENESTHO. 



Entire .surface of the shell marked by spiral cords. 

 Shell elongate-conic. 



Shell large, adult more than 5 mm. long yrammatospira, p. 185. 



Shell small, adult less than 2.5 mm. long pharcida, p. 185. 



Shell elongate-ovate or ovate. 



Last whorl marked by about 40 spiral cords exara, p. 186. 



Last whorl marked by less than 20 spiral cords. 



Spiral cords 2 between the sutures of the last whorl . . . .ziziphina, p. 186. 



Spiral cords 3 between the sutures of the last whorl recta, p. 187. 



Spiral cords 4 between the sutures of the last whorl. 



Basal cords 3 amilda, p. 187. 



Basal cords 4 . 



Shell ovate rallipyrga, p. 188. 



Shell elongate-ovate. 



Spiral sculpture very strong farma, p. 188. 



Spiral sculpture very feeble enora, p. 189. 



Basal cords 7 chilensis, p. 189. 



Basal cords 11 fetella, p. 189. 



Spiral cords 6 between the sutures of t\w last whorl . 



Basal cords 5 Injpocurta, p. 190. 



Basal cords 6 nquisculpta, ]). 191. 



Basal cords 8 harfordensis , p. 191. 



Base of 1 lie shtll only marked by spii-al cords sublirulata, p. 192. 



