Diagnosis
Shell globular, sculptured with numerous strong axial ribs, fine spiral threads on teleoconch II; protoconch with flocculant ornamen-tation.

Description
Shell trochiform, globular, inflated, medium size (up to 1.8 mm in diameter), suture ap-proximately one width of selenizone below selenizone. Protoconch of approximately one whorl, 160-205 µm in diameter, with flocculant sculpture; margin of protoconch convex, without apertural varix. Teleoconch I of 1/2 to 2/3 whorls, with single spiral cord in position of selenizone on early teleoconch I, disappearing close to onset of selenizone; 10-21, occasionally bifurcated, axial ribs. Teleoconch II of up to two rounded whorls, with convex shoulder. Shell surface cancellate: axial sculpture of strong ribs, 26 on shoulder of first whorl, 31-34 on last whorl (occasionally bifurcating near selenizone); approximately 60 on base; spiral threads weak, beginning at start of selenizone, gradually increasing in number with growth, approximately 18-20 at apertural margin, 25 on base. Selenizone at periphery, relatively wide, sculptured with low axial ribs, surrounded by narrow keels. Umbilicus open, wide, deep; walls with continuous transition to base; funiculus present. Ap¬erture rounded. Animal unknown.

The type material of Anatoma conica is probably lost; it was originally deposited in the BMNH (Gray, 1854), but not found currently there (Geiger, pers. obs.; K. Way, pers. comm.). However, we consider the original description and illustrations to be adequate to recognize this species; in addition, the topotypic specimens examined during this study allowed us to confirm the identity of this taxon.
Anatoma conica is most similar to the Antarctic Thieleella amoena (Thiele, 1912), from which it differs by a wider shoulder, stronger axial ribs, and flocculent (instead of reticulate) protoconch ornamentation. Other similar species are Thieleella gunteri (Cotton & Godfrey, 1933) from southern Australia (Geiger & Jansen, 2004a) and Thieleella flemingi Marshall, 2002, from New Zealand, which also show reticulate protoconch sculpture. Anatoma conica can be easily separated from the Antarctic Anatoma euglypta (Pelseneer, 1903) by its more globular shell, as opposed the overall biconical shape of A. euglypta. In addition, Anatoma conica has fewer but more elevated axial ribs, particularly on the shoulder, while the axials are more numerous and the strength of the sculpture is more homogeneous on shoulder and base in A. euglypta.
The specimens from Burdwood Bank, previously referred by Melvill & Standen (1912) to Scissurella supraplicata (NMSZ 1921.143.596) are here reidentified as Anatoma conica.

Magellanic region.