Partulina horneri

The length of the shell attains 24 mm, its diameter 18 mm. (Original description) The shell is sinistral, minutely perforate, and thin, with a globose form and a short, acutely conical spire; the apex is acute. Its surface is shining and striated by fine incremental lines; under a lens, it exhibits very close, delicate, decussating spiral striae. The whorls of the protoconch are faintly cross-lined. The shell is dull white and is encircled at the periphery by a faint brown zone, which continues onto the suture. A very small patch of the same colour also surrounds the umbilicus. There are six whorls. The upper five are slightly convex, whereas the body whorl is very greatly inflated and forms the greater part of the shell. The suture is distinctly impressed. The aperture is oblique, subrotund, and very large. It is white internally and distinctly shows the external peripheral band. The peristome is margined with light brown, is rather thin, and is very slightly thickened internally; it is expanded, with narrowly reflexed basal and columellar margins. Its extremities converge slightly and are united by a thin callus. The columella is light brown, very slightly developed, plain, and smooth. When in motion, the animal is longer than its shell. The mantle is black and margined with grey. …