Investigation and Plate Numbering Scheme

The work presented within these Field Notes follows a single continuous programme of microscopic investigation, but is organised under two related classification schemes.

The earlier Scheme of Structural Investigations (SI) formed the initial framework for study and was used to catalogue the first series of specimens and plates. Each plate from this period is therefore labelled according to that scheme (e.g. SI–II–028), reflecting both its thematic placement and its order within the sequence of observations.

Subsequently, a more extensive and refined framework — the Programme of Microscopic Investigations (PMI) — was introduced. This expands on and, in some cases, reorders the original scheme, providing a broader and more systematic coverage of microscopic structures.

As a result, there’s a partial correspondence between the two systems, though not a strict one-to-one mapping. Some sections of the earlier scheme align directly with those of the later programme, while others are redistributed or have no direct equivalent.

Correspondence Between Schemes

The relationship between the two systems may be summarised as follows:

Note: Certain SI sections correspond to multiple PMI sections, reflecting the expansion and reorganisation of subject matter in the later programme.

Present Numbering

During the current phase of work, investigations are being conducted according to the PMI framework, but plates continue to retain their original SI identifiers, in order to preserve continuity with earlier records and to avoid the unnecessary duplication of specimens and illustrations.

So a plate labelled SI–II–028, for example, remains catalogued under the earlier scheme, even where its subject would fall under PMI–III.

Future Transition

After the close of 2026, while plates labelled according to the earlier SI series will remain intact, any new plates will be catalogued under the Programme of Microscopic Investigations (PMI) (e.g. PMI–III–001).