[Illustration: S-SHAPED ENAMELLED BRONZE FIBULA, LOCALITY UNKNOWN; NOW IN THE BRITISH MUSEUM SCALE 1/1 LINEAR] [Illustration: S-SHAPED FIBULA OF ENAMELLED BRONZE, FROM NORTON, E. RIDING OF YORKSHIRE; NOW IN THE BRITISH MUSEUM SCALE 1/1 LINEAR] Although the safety-pin type of fibula was, in its earlier stages, made out of a single piece of wire, it may be considered to consist of four different parts, each of which performs a function of its own, namely, (1) the head, containing the spring or hinge; (2) the tail, containing the catch, or locking apparatus; (3) the body or framework, connecting the head with the tail; and (4) the pin, moving on a hinge or spring at one end and with the pointed end fitting into the catch. In all fibulæ derived from the safety-pin the pin is straight and the body bent into a more or less arched shape, like a bow. An infinite variety of forms were produced (1) by increasing the number of coils in the spring and their size; (2) by expanding the tail end into a thin triangular plate; and (3) by increasing the thickness of the body, or by making a coil in the middle of its length to act as a secondary spring. Much the most important modifications, however, in the safety-pin brooches were those which gradually led up to the harp-shaped, T-shaped, and cruciform fibulæ of the Romano-British period. Dr. Arthur J. Evans, in his paper in the _Archæologia_ (vol. lv., p. 179) on “Two Fibulæ of Celtic Fabric from Æsica,” has traced the evolution of the harp-shaped fibula from the bow-shaped fibula in a most interesting way. The different stages in the process appear to have been as follows:— (1) The tail end of the fibula was extended and bent backwards so as to make an =S=-shaped curve with the bow; (2) the retroflected end of the tail was fixed to the middle of the convex side of the bow by means of a small collar, made in a separate piece; (3) the whole of the back was formed out of one piece of metal, with the collar surviving as a mere ornament; and (4) the triangular opening at the tail, bounded by the retroflected end, part of the bow, and the catch for the point of the pin, was filled in solid with a thin plate. It will be noticed that during this process of evolution the extended and retroflected end of the tail has become part of the continuous curve of the convex side of the bow, whilst what was previously one-half of the outside of the bow is now on the inside of the triangular plate at the tail end. This, together with the expansion of the head to suit the increased number of coils in the spring, produced the characteristic harp-shape of the Romano-British fibula, in many of which the knob ornament in the middle of the back is the last survival of the collar for fixing the retroflected end of the tail in its place.