| At the posterior of the body, the pleurae were fused into a flattened tail-like segment, or pygidium. |
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| As noted above, it closely resembles the syntype pygidium of E. acadicus, and is tentatively assigned to that species. |
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| Agnostids have only two or three segments between the cephalon and pygidium. |
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| The pygidium is complete and has a short axis that has a well-defined axial ring. |
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| A pygidium with an attached thoracic segment represents a meraspid stage of the species. |
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| The pygidium, like the cephalon, was a structure in which segments were fused together. |
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| Members of the Agnostina have only two segments between the cephalon and pygidium, and never have cephalic sutures. |
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| The post-segmental posterior terminus is called the pygidium. |
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| Unlike the agnostids, polymerid trilobites typically have more than two or three thoracic segments, and the pygidium is usually smaller than the cephalon. |
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| Longacre emphasized unequally divided pleurae on the pygidium and the presence of an occipital spine as characters separating Calvinella from other dikelocephalids. |
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| The pygidium is semi-elliptical in outline, nearly as long as wide, with the anterior margin forwardly arched. |
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| The structures such as genitalia, antenna, abdominal segments IX-X, and pygidium were placed on glycerin mounts. |
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| The pygidium of the male appears straight downwards from above. |
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| The shell-boring polychaete species were identified on the basis of fifth setiger chaetae, prostomium and pygidium morphology, and branchiae distribution. |
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