Shell cream, thin, small, ovate, depressed, possessing a striking ornamentation of rounded and oval pits all over the surface giving it a somewhat honeycombed appearance. Perforation large, oblong, almost centrally situated, barely one-sixth the length of shell. Interior white, yellow, occasionally with narrow brown streaks towards the perforation which is bordered with a narrow, white callus rim. Size: 0,5 inch.

Pitted Keyhole Limpet. Shell ovate, depressed, conic, rather thin, white; sculpture of peculiar round to ovate depressions becoming more elongate towards the margin; perforation oval, pinched in laterally, slightly wider posteriorly, one-fifth the diameter of the shell, interior margin calloused, forming a regular ovate rim; muscle impression marginal. Radula has the central tooth narrower than in Scutus anutinus, about half as wide, and it is turned over at the cutting edge and base; laterals are slightly wider than those of S. anatinus, four in number and then the major lateral which is like that of D. lincolnensis but slightly different in shape; marginals are embedded in a basal plate and the roots of the teeth can be seen in the plate. Diameters 15 mm. and 10.5 mm., height 3.5 mm.
Radula formula M+l + (4+l+4)+l + M, : 36 to 50 rows of teeth. The central teeth consist of one broad median tooth with four smaller on each side, the fourth from the centre tooth having a truncated apex; the single lateral is very large, tricuspid, overlapping the centrals; the marginals represented by M in the formula, are in two rows each of 21 very fine long teeth, serrated at their extremities and fixed at their base along one side of a triangular plate, the rows parallel to the side of the radula; this is bilaterally asymmetrical, and the chief characteristic is the huge size of the single lateral; three specimens of small, medium, and large size had 40, 43 and 50 rows of teeth respectively, the number increasing with the growth of the animal, but not proportionately, as does the size of the individual teeth.

This species is readily separated from Amblychilepas javanicensis (Lamarck, 1822) by its more oval form, the absence of brown colour-rays and the presence of the honeycombed surface.

The species enjoys a rather wide distribution from New South Wales, Tasmania, Victoria, through Bass Strait to South Australia and Western Australia.

Animal active, much larger than the shell: under rucks at low tide. The surface resembles the pattern of a Bryozoa, such as Retepora granulata which is occasionally attached to South Australian shells. The young shell in the egg appears to have holes penetrating the shell in place of the usual malleations of the adult shell. The white shell may be sometimes radially rayed with light brown and the internal callus may be brown. Etym.: catenatus, a chain; sculpture resembles links of a chain joined together like chain mail. Sometimes taken living in associa-tion with a grey Ascidian. The shell, except for the apical fissure is entirely covered by the greyish mantle. Specimens taken by J. O. Wilson at Port Willunga on the reef at low tide showed some variations as follows:
- Mantle red on dorsum, rest of mantle and foot buff. Eggs beneath foot.
- Mantle and foot buff
- Mantle black, foot buff.
- Mantle buff, foot buff, black spots on mantle round edge of shell.