116 PYRAMIDELLID.E. 



sonce. From that shell it is distinguishable by its smaller 

 size^ conical rather than cylindrical shape, having fewer 

 whorls and flexnous stride, and especially in the mouth 

 being entire instead of notched at the base, and in the 

 outer lip not being expanded nor united with the inner 

 lip. It is the smallest known species of Odostomia. 

 The Chemnitzia minima of Homes, from the miocene 

 formation near Vienna, is different from this. 



2. O. Nivo'sA"^, Montagu. 



Turbo mvosKS, Mont. Test. Br. (ii.) p. 326. 0. cylinclTica, F. & H. iii. 

 p. 287, pi. xcvi. f. 7. 



Shell forming a cylindrical cone, not very thin, transparent 

 and glossy: sculpture, 2 or 3 narrow spiral ridges on the peri- 

 phery, and a single stronger one immediately below the suture 

 of each whorl, besides close-set and extremely fine but obscure 

 flexuous striae in a longitudinal direction ; one of the spiral 

 ridges usually encircles the base of each upper whorl ; under 

 a microscope the whole surface appears more or less covered 

 with numerous indistinct fine spiral lines : colour white, mth 

 occasionally a slight fulvous tint : spire tapering to an abrupt 

 rounded and inverted point, the apex being sunk or involved 

 in the extremity of the spire : ivliorls 4-5, somewhat com- 

 pressed ; the last exceeds all the rest in length and bulk : 

 suture rather deep, distinctly marked by the uppermost spiral 

 ridge : mouth oval, much narrower above than below, where 

 it is expanded ; it is scarcely equal in length to one -fourth of 

 the spire : outer lip flexuous, inflected and contracted at the 

 upper part : inner lip not very thin, adhering to the pillar, 

 slightly reflected over the base, and occasionally united with 

 the outer Hp : umbilicus none ; but a narrow chink may be 

 observed in aged specimens : tooth small, usually concealed 

 behind the pillar: operculum yellowish, strongly striated or 

 furrowed in the line of growth, the striae being more close-set 

 and flexuous towards the outer side; spire very short and 

 nearly terminal. L. 0-0625. B. 0-0325. 



Habitat : The lower part of the littoral zone, and the 



* Snowy, for snow-white ; properly nivea. 



