General description (after 48 shells from 11 localities). — The shell is rather slender, oval-conical, with a blunt top. The protoconch is of type B. There are four (rarely five) almost flat or slightly convex teleoconch whorls. The suture is deep and somewhat open, its inclination is variable, but generally strongly oblique, which gives the shell a screw-shaped appearance. The initial whorls are relatively higher than in most Ckrysallida of about the same length. The ribs are more or less vertical; they are slightly curved, on the last whorl somewhat sinuous. The ribs are moderately broad and high, variable in number, thus the interstices .vary from narrow to broader than the ribs. In most cases, the ribs continue to the base, occasionally they fade away around the periphery. Although the spiral ridges are only present between the ribs, they are nevertheless more pronounced than in most other Chrysallida. The oldest teleoconch whorl has one spiral, just above the suture. The last whorl has three spiral ridges, the lowest one at the level of the upper side of the aperture, the highest one just under the middle of the distance suture-upper edge of aperture, the central spiral just in between. The other whorls have two spiral ridges, the apical one clearly under the middle of the whorl. All these spirals are rather widely spaced. Apart from the main spirals, there are many microspiral-striae between the ribs on all whorls (only visible on fresh and clean shells). The aperture is oval; only when turning the shell far to the left, a very faint tooth-pleat can be seen. There is an umbilical groove, often hidden behind the columellar lip.
Length 1.5-2.6 mm, LW 48-59%, A 25-31% L/B 2.6-3.0, B/b 1.3-1.6 (based on 12 shells).

AS Chrysallida clathrata
Habitat: it lives in the infralittoral zone.
Distribution: it is collected in several localities of the Mediterranean but always rare; was found at Secca di Capo Vita (Elba Is. - Tuscan Archipelago - Italy), at 40 m depth.
Notes: this species is cylindrical in outline, a little bit pupoid, whorls either flat-sided or a little bit convex, suture broad and oblique. First whorls of teleconch are higher than those of its similar ones. Protoconch is type B. Axial ribs are more or less vertical, a little bit sinuous on last whorl up to columella. Spiral sculpture, present in the interspaces, is made by strong little cords, three of them on last whorl and two of them on previous whorls. The upper one is always placed at about half whorl. Aperture ovoidal in form with one small tooth not much visible. Also umbilicus is just sketched. Identification of this species is not difficult whether its main characteristics are duly taken into consideration that is: height of first whorls, the three spiral little cords quite prominent on last whorl, the two ones on the previous whorl and columellar fold practically missing. C. emaciata is slimmer, with whorls more convex, tooth more prominent and with a spiral streaking at the base. C. obtusa has same spiral sculpture but weaker, suture deeper, first whorls less high and a tooth more prominent. Average measures of adult specimens are around 2.5 mm in height.

Considering the main characters of C. clathrata, identifica¬tion is not difficult: the high initial whorls, a somewhat screw-shaped appearance, the three, more prominent, spiral ridges on the last whorl and two on the others, and a very faint tooth-pleat.
C. jeffreysiana has about the same appearance, but is on average larger, coarser, and has no spiral ridges.
C. emaciata is more slender, has more convex whorls and the initial whorls are clearly shorter. There is a more prominent tooth and spiral striae on the base.
The shells of C. obtusa from the Canary Islands with three spirals on the last whorl and two on the penultimate whorl, differ from C. clathrata by having flat whorls, a narrow, shallow and not very oblique suture. The older whorls appear to be not so high as in C. clathrata and there is indeed a hidden, but prominent tooth.
All other Chrysallida with three spiral ridges on the last whorl and two on the penultimate one, are very different in shape.

An uncommon species, to the authors only known from south Portugal and the Mediterranean. Fretter, Graham, Andrews (1986) report it from the Mediterranean north to the British Isles.