Mangilia.~] 



GASTROPODA. 



495 



Shell small, fusiform ; spire rather short, sometimes scalar ; proto- 

 conch with convex whorls and papillate nucleus ; whorls with axial 

 riblets, sometimes crossed by spiral striae, the last whorl equal or superior 

 to half the height of the shell ; aperture narrow, sides subparallel ; 

 canal short, not notched at its base ; outer lip thickened by the last 

 riblet, smooth inside, with a moderately deep sinus at the suture ; 

 columella straight, smooth. 



Distribution. A great number of species, inhabiting all portions 

 of the globe. 



Fossil in the Tertiary from the Eocene. 



KEY TO SPECIES. 



A. Spire of the same height as the aperture, or but little higher. 

 a. Axial riblets on a whorl less than 18. 



b. Axial riblets 9-10, continuous over the whorls ; minute 

 close spiral threads ; spire a little higher than the 

 aperture . . . . . . . . . . Goodingi. 



bb. Axial riblets 10-16 ; many more or less distinct spiral 

 strife ; spire a little higher than the aperture ; base 

 usually with a brown band . . . . . . Sinclairi. 



bbb. Axial riblets about 15, faint, flattish ; microscopic 

 spirals, 3 of which are more distinct on the penulti- 

 mate whorl ; spire of the same height as the aperture murrhea. 

 aa. Axial riblets about 18 on a whorl. 

 b. Protoconch smooth. 



c. Spire-whorls with 6 spiral cords, points of inter- 

 section nodulous . . . . . . . . cophinodes. 



cc. Spiral cords 2 on the penultimate and 4 on the 



body-whorl . . . . . . . . quadricincta. 



bb. Protoconch microscopically spirally striate ; axial rib- 

 lets llexuous ; spiral sculpture microscopic . . flexicostata. 



bbb. Protoconch with smooth nucleus, the second whorl 

 reticulate ; strong equidistant spiral cords, which 

 do not pass over the riblets ; suture submargined subaustralis. 



B. Spire 1 times the height of the aperture. 

 a. Protoconch smooth. 



b. Axial riblets 9, penultimate whorl with 3 prominent 



spiral cords . . . . . . . . . . infanda. 



bb. Axial riblets about 13, numerous spiral threads . . dictyota. 

 bbb. Axial riblets 15-20. 



c. Axial riblets 16, nearly continuous over the whorls ; 

 penultimate whorl with 8 spiral threads, 4 of 

 which are on the shoulder ; crossing-points 

 gemmate ; suture lightly margined . . . . munda. 



cc. Axial riblets 15-20 : penultimate whorl with 8 

 spiral threads, 3 of them on the shoulder ; 

 suture simple . . . . . . . . protensa, 



aa. Protoconch with a carinate nucleus ; axial riblets 10, 



strong, nodulous ; 3 spiral cords . . . . . . devia. 



ana. Protoconch angled, with 4 spirals ; axial riblets 15-16 ; 



fine spiral threads . . . . . . . . epentroma. 



