(Fig. 10 A-D)
Eucalathis magna Cooper, 1981a: 17, pl. 1, figs 1-6. — Zezina 2010: 1187.
MATERIAL EXAMINED. — South Madagascar. ATIMO VATAE, stn DW 3529, 1 bivalved specimen.
DEPTH RANGE. — 402- 207 m.
MEASUREMENTS. — Length 13.4 mm, width 10.7 mm, thickness 4.8 mm.
REMARKS
Species of the genus Eucalathis are common in all the oceans of the world and range greatly in depth. Six species have been recorded from the Indian Ocean: E. rotundata Cooper, 1981; costellata Cooper, 1981; fasciculata Cooper, 1973; magna Cooper, 1981; murrayi (Davidson, 1878); and rugosa Cooper, 1973 (Logan 2007). E. magna is very rare in the investigated material, represented by only one specimen. It was originally described, also based on one specimen, from the West of Heard Island at a depth of 790 m by Cooper (1981a). The present finding extends its geographical range.
This species is characterized by a large size for the genus and almond-like outline. Both in outline and ornamentation E. magna strongly resembles Terebratulina species. Cooper (1981a: 17) indicated the absence of deltidial plates, however, although minute they are present, both in the specimen from off South of Madagascar and the holotype.