General description (after 84 shells from 17 localities). — The shell is slender, cylindrical, with a blunt top. The protoconch is of type B. There are four to five (rarely six) flat teleoconch whorls, suddenly bent inwards very near to the upper and lower suture. The suture is narrow and deep, noticeably oblique. Generally the ribs are narrow and sharp. Since there are many, close together, the interstices are narrow as well. Only occasionally the ribs are somewhat more distant (fewer ribs) and thus the spaces in between are broader. The ribs are vertical and straight to slightly flexuous. They continue to the base, or decrease around the periphery of the last whorl. The initial whorls have one spiral ridge on their base, sometimes two, in which case the lower one lies practically within the suture and is difficult to observe. The last whorl has two spiral ridges, the lower one on the level of the upper edge of the aperture, the other just above it. All spirals are very thin and often not easy to distinguish. Furthermore, there is a microstructure of spiral striae between the ribs on all whorls. The aperture is narrow oval, the small tooth is visible on turning the shell to the left. There is an insignificant umbilical chink.
Length 1.7-2.6 mm, LW 43-53%, A 24-34%, L/B 2.8-3.3, B/b 1.3-1.4 (based on 18 shells).

See under C. emaciata for comparance with this species. Some specimens of C. clathrata do resemble C. suturalis somewhat more. The general shape of the first species is coarser (L/B lower), there are fewer and heavier ribs, the suture is more open and on every whorl there is one more, much coarser, spiral ridge. The other Chrysallida with two spirals on the last whorl and one on the others are generally coarser in shape, much more conical, most are longer and have a more pronounced tooth; the latter is strikingly different from that of C. nanodea (see below). In this context, it is remarkable that, from some locations of the Canary Islands, there are specimens of C. obtusa with a reduced tooth and three spirals on the last whorl somewhat resembling C. suturalis. The authors did not find shells with more than two spiral ridges on the last whorl, as stated by Fretter et al. (1986).

Sizes and ratios given in the literature only rarely agree, even the quoted length of shells can differ considerably; thus, Van Aartsen mentions L 1.5-2.0 mm, LW<50% and L/B ± 2.6. About half the number of the shells in the material investigated, has a length of between 2.0 and 2.6 mm, and only in this length interval LW is <50%. Shells in the length interval given by Van Aartsen all have an LW higher than 50%, at 1.5 mm even 57%. Fretter, Graham & Andrews (1986) report LW 51-57%, which is largely outside the area in the present investigation (LW 43-53%) and not at all in accordance with the LW<50% of Van Aartsen. The ratio L/B 2.4-2.6 given by Fretter et al. is even completely different; that of the present authors is 2.8-3.3 and Van Aartsen records ± 2.6.

The authors have seen this species only from the entire Mediterranean area. C. suturalis is also recorded from the Atlantic coast of Europe, north to the British Isles (Rolan Mosquera, 1983; Fretter, Graham & Andrews, 1986). Looking at their SEM photography, it is clear that this shell is not C suturalis, but a specimen of the variable C. obtusa, cf. L/B 2.3, C. suturalis 2.8-3.3 and B/b 1.6, C. suturalis 1.3-1.4; also the rib pattern is very different. Thus the record of Fretter et al. is doubtful (cf. Discussion).