About Oxychilus navarricus (Bourguignat, 1870)
Refer to the entry on gastropod shell for terminology related to this description. The shell of Oxychilus navarricus measures 4.5–6 mm in height and 7–13 mm in width (equivalent to 0.18–0.24 by 0.28–0.51 inches). The shell is thin, has a light horny yellowish color, is whitish near the umbilicus, very shiny, and almost smooth. Its overall outline is nearly globulous. It has 4.5 to 6 weakly convex whorls marked by a weak suture. The width of the last whorl is 1.5 times or less that of the preceding whorl, and the last whorl is well rounded on its lower side. The umbilicus is not very wide, measuring between 1/8 and 1/7 of the shell’s total diameter. For genitalia: the internal ornamentation of the proximal penis consists of more than seven longitudinal pleats. These pleats are sometimes straight and distinct, and sometimes wavy, slender, and connected by lateral projections that create a reticulate appearance. This species has been recorded occurring in multiple countries and islands, including Great Britain, Ireland, the Netherlands, Switzerland, and introduced populations in Canada, as well as other areas.
