ODOSTOMIA. 347 



0. INSCULPTA, Mont. PI. 77, fig. 91. 



Thin, semitransparcnt, glossy, with distinct spiral incised lines, 

 ■with inconspicuous longitudinal striae near the suture, white ; 

 whorls 6, each narrowly, thickly rimmed just below the suture, 

 which is sliglitl}' channeled ; umbilicus narrow ; tooth incon- 

 spicuous but alwa^'S present. Length, 3-75 mill. 



Northern Europe. 



It is 0. obliqua, Loven. 



0. UMBiLiCARTS, Malm. PL 77, fig. 92. 



Shell thin, transparent, ver^' gloss^v, white ; whorls 5-6, with 

 deep suture; umbilicus verj' distinct, but small; tooth small, 

 but prominent. Length, 2 5 mill. 



Northern Europe. 



Owing to the transparency' of the whorls, the periphery of 

 each appears like a narrow band round the top of the suc- 

 ceeding one. 



0. MiCHAELis, Brugnone. PI. 77. fig. 93. 



Oblong ovate, smooth, shining; whorls 6, slightly convex, 



columella strongly uniplicate. Length, 5*5 mill. 



3Iediterranean Sea. 

 0. RissoiDES, Hanley. PL 77, figs. 94-96. 



Thin, transparent, glossj', with microscopical growth-lines 

 and spiral striae, pale yellowish wbitQ, or whitish ; whorls 5, 

 convex, rapidly enlarging, suture rather deep, in fresh speci- 

 mens with a darker baud ; umbilicus usuall}' none, or a mere 

 chink or indentation ; tooth small and partly concealed. 



Length, 3 mill. 



Europe. 

 Yar. ALBA, JeflTreys. 



Thinner, spire produced, suture deeper and more oblique, 

 umbilical chink ver}- distinct. 



Yar. NTTiDA, Alder. Fig. 95. 



Whorls more ventricose and umbilicus distinct. 



Yar. GLABRATA, Forbcs and Hanley. Fig. 96. 



Nearly oblong, nucleus of spire exposed and mamillary-, 

 suture deep. 



