ODOSTOMTA. 34 7 



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



Thin, semitransparent,gloss} T ,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 slightly channeled ; umbilicus narrow ; tooth incon- 

 spicuous but always present. Length, 3 - 75 mill. 



Northern Europe. 



It is 0. obliqua, Loven. 



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



Shell thin, transparent, very glossy, white ; whorls 5-6, with 

 deep suture; umbilicus very distinct, but small; tooth small, 

 but prominent. Length, 25 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. 



Mediterranean Sea. 

 0. RISSOIDES, Hanley. PI. 77, figs. 94-96. 



Thin, transparent, glossy, with microscopical growth-lines 

 and spiral stria?, pale yellowish white, or whitish ; whorls 5, 

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

 mens with a darker band ; umbilicus usually none, or a mere 

 chink or indentation ; tooth small and partly concealed. 



Length, 3 mill. 



Europe. 

 Yar. ALBA, Jeffreys. 



Thinner, spire produced, suture deeper and more oblique, 

 umbilical chink very distinct. 



Yar. NITIDA, Alder. Fig. 95. 



Whorls more ventricose and umbilicus distinct. 



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



Nearly oblong, nucleus of spire exposed and mamillary, 

 suture deep. 



