Towards the end of the Bronze Age the safety-pin was arched into a bow, so as to include a greater amount of stuff in its compass.
In the older Iron Age or "Hallstatt period" the bow and its accessories are thickened and modified in various directions, so as to give greater rigidity, and prominences or surfaces for decoration. The chief types have been conveniently classed by
Montelius in four main groups, according to the characteristic forms:—
I. The wire of the catch-plate is hammered into a flat disk, on which the pin rests (fig. 2)
Fig. 2.—Type I. with disk for catch-plate.
II. The bow is thickened towards the middle, so as to assume the "leech" shape, or it is hollowed out underneath, into the "boat" form. The catch-plate is only slightly turned up, but it becomes elongated, in order to mask the end of a long pin (fig. 3).
III. The catch-plate is flattened out as in group I., but additional convolutions are added to the bow (fig. 4).
IV. The bow is convoluted (but the convolutions are sometimes represented by knobs); the catch-plate develops as in group II. (fig. 5). For further examples of the four types, see Antiquities of Early Iron Age in British Museum, p. 32.
Among the special variations of the early form, mention should be made of the fibulae of the geometric age of Greece, with an exaggerated development of the vertical portion of the catch-plate (fig. 6).