Patella citrullus: "Shell sub-diaphanous, thin sub-conical, moderately elevated, summit prominent; apex anterior, acute, feebly incurved, usually somewhat eroded; a great number of faintly elevated lines, studded with fine tubercles or asperities, radiate from it, and become obsolete about half way towards the margin. Striae of increment coarse and irregular, overlaying each other, so as to give the shell a rude, concentrically squamose aspect externally; disc nearly oval, a little narrowed anteriorly; margin very thin and sharp, finely and irregularly undulated. External colour a dusky olive-green, with a shade of brown showing through it, ornamented with concentric, undulating lines of obscure white. Interior greenish-white, with bright iridescent reflections; a slight spatulaform deposit at the fundus, bluish at the edges and forepart, passing into greenish towards the middle and posterior portions." Length 45 mm; Width 32 mm; Height 7.0 mm

Patella citrullus: The writer (Powell) has not seen examples of this species which appears to be related to candei. Pilsbry (1891, I.e.) remarked that the external surface resembles the skin of a cucumber.

Patella citrullus: Funchal, Madeira.