. Bulletin of the British Museum (Natural History), Geology. . Fig. 13 Myofossa (Ragozinia) amatopensis (Thomas). Figs 13a-b, Permian, 'Goniatite' bed, Parinas Quebrada, Amatope Mountains, north- west Peru; SM A4971, Barrington Brown Collection, holotype; Fig. 13a, top view; Fig. 13b, left side. Figs 13c-f, Lower Permian, Sakmarian, Fossil Cliff Formation, Irwin District, Western Australia; BM L9498; Fig. 13c, right side; Fig. 13d, top view; Fig. 13e, anterior view; Fig. 13f, leftside. All xl. with the specimens described by Dickins and there is now adequate material to indicate that this is a
. Bulletin of the British Museum (Natural History), Geology. . Fig. 13 Myofossa (Ragozinia) amatopensis (Thomas). Figs 13a-b, Permian, 'Goniatite' bed, Parinas Quebrada, Amatope Mountains, north- west Peru; SM A4971, Barrington Brown Collection, holotype; Fig. 13a, top view; Fig. 13b, left side. Figs 13c-f, Lower Permian, Sakmarian, Fossil Cliff Formation, Irwin District, Western Australia; BM L9498; Fig. 13c, right side; Fig. 13d, top view; Fig. 13e, anterior view; Fig. 13f, leftside. All xl. with the specimens described by Dickins and there is now adequate material to indicate that this is a very widespread species. The matrix of the newly discovered Australian specimen, BM L9498, is that of the Fossil Cliff Formation. The label with the specimen reads Trwin District, Western Australia. Presented H. P. Woodward, May 1892'. The specimen apparently came from Fossil Cliff. Although Runnegar (1969: 285) has suggested this species belongs to Australomya, the features of the escutcheon show that it belongs to Myofossa. When we compared the Australian material with Thomas' Peruvian holotype we were unable to find any significant differences. The Western Australian specimens and the holotype show considerable similarity to the Carboniferous species assigned in this paper to Myofossa, and especially to S. (Ragozinia) gorskyi from the Kungurian of the USSR, though the specimens from Western Australia are rather larger. Muromzeva (1984) distinguished a separate species, M. (R). dembskajae, which had a much more attenuated posterior. We have not been able to examine any of her material, but we suspect the differences may be due to crushing. The posterior part of the shell, however, is more upturned in M. (R.) amatopensis than in the Carboniferous species, probably reflecting adaptation to deeper burrowing. M. (R.) amatopensis differs from its contemporary, M. subarbitrata, in lacking a concave anterior margin, its much finer ribbing and in being upturned at the back. Myofossa
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