Conway, The Italic Dialects, 352) shows a final -s and a medial -d-, both apparently preserved from the changes which befell these sounds, as we shall see, in the dialect of Iguvium.
The interpunct is double with the Umbrian alphabet, single and medial with the Latin.
The longitudinal system is discontinuous, and is subdivided into proximal, medial and distal portions.
The medial portion forms radiating tracts of fibres, the so-called " bell-muscles " running underneath, and parallel to, the radial canals; when greatly developed, as in Tiaridae, they form ridges, so-called mesenteries, projecting into the sub-umbral cavity.
Taking the Atlantic as our simplest type, we may say that the surface of an ocean basin resembles that of a mighty trough or syncline, buckled up more or less centrally in a medial ridge, which is bounded by two long and deep marginal hollows, in the cores of which still deeper grooves sink to the profoundest depths.