. Bulletins of American paleontology. Australian carpoids: Gill and Caster 45 Rhe}wcystis Dehm, 1933—Lower Devonian, Germany Austral Province Placocystella Rennie, 1936—Lower Devonian, South Africa Australocystis Caster, 1955—Lower Devonian, Brazil The subfamily Placocystitinae (here emended from Placocystinae Caster, 1952) has been erected to receive Phcocystites and the Australo- cystinae (Caster, 1955) to receive Australocystis. The other genera have not yet been referred to subfamilies. The three genera of the Boreal paleo- geographic province have a ""P" somatic plate in th
. Bulletins of American paleontology. Australian carpoids: Gill and Caster 45 Rhe}wcystis Dehm, 1933—Lower Devonian, Germany Austral Province Placocystella Rennie, 1936—Lower Devonian, South Africa Australocystis Caster, 1955—Lower Devonian, Brazil The subfamily Placocystitinae (here emended from Placocystinae Caster, 1952) has been erected to receive Phcocystites and the Australo- cystinae (Caster, 1955) to receive Australocystis. The other genera have not yet been referred to subfamilies. The three genera of the Boreal paleo- geographic province have a ""P" somatic plate in the middle of the carapace; the carapaces of the Austral genera have not yet been described. In the Boreal Placocystida there is an overall increase in the number of carapace plates from the Middle Ordovician Ateleocystites to the Lower Devonian genera, but this does not apply to the Austral genera, which apparently. Text-fig. 10.—Placocystites jorbesiaiius de Koninck, Upper Silurian (Wenlock) of Great Britain, after Bather's (1900) restoration from the type material. A. Plastron view. B. Carapace view. Lettering after Caster, 1952, 1954, from analyses of Enoploura of the American Ordovician and Rhenocystis from the Rhenish Lower Devonian respectively. M2 and M5 indicate possible areas of the placocystitid Ml and MA plates which were later differentiated into separate plates—or are here indistinguishably fused into the Ml and M4 plates; x—indicates the general posi- tions in the Ml and M4 plates of the lam plates of Enoploura and Rhenocystis, (likewise either fused into or not differentiated from the Ml and M4 plates); y—indicates the general position of the ax plates in Enoploura, at the base of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Paleontological Research Institution (I
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