In the developed B.F. vases the same principles are observed to some extent, especially where friezes of animals are introduced; but there is much greater freedom of treatment within the limits of the field available. Generally speaking, however, all designs on B.F. vases may be regarded as following one of the three methods of architectural composition—the frieze, the pediment, or the metope. The frieze style, which is seen on the shoulders of hydriae, the exteriors of kylikes, and sometimes on the bodies of amphorae, oinochoae, or lekythi, implies a series of figures, all turned in the same direction, but without any central point for the action, as in processions of warriors, dances of Satyrs and Maenads, and so on. In the pediment style of composition the essential feature is a centre-point, in which the interest of the subject is concentrated, as in such scenes as the Birth of Athena[2013] or Theseus killing the Minotaur.[2014] The central group is then flanked by figures immediately interested in the action (Eileithyia and Hephaistos, or Ariadne, in the instances quoted; Athena and Iolaos at the labours of Herakles); and the ends of the pediment, so to speak, are occupied by groups of bystanders, often nameless and uncharacterised, who are in fact only included to fill up the space required. The metope style, which only admits of three, or at most four, figures, was found convenient for all the vases with subjects on panels, where space was restricted, and also on the kylikes of the “minor artist” class, on which a limited use of figures was preferred, and on those of later date where the space was mainly taken up by the large eyes. But in all these cases—friezes, pediments, or metopes—one thing was held to be essential: the correspondence of the two halves of the design (except in friezes), producing perfect symmetry in the composition. Lastly, there are a limited number of cases where a single figure was found sufficient, as in the interior of kylikes, on the circular pinakes,[2015] and sometimes on the vases where the large eyes take up most of the space.[2016] Subordinate designs, bordering the main design of an amphora above or below, or decorating the cover, are usually in the form of animals or chariot-races, in the frieze style of composition. Similar friezes are sometimes also found (in the old B.F. method) on R.F. vases, and even on the kraters of Southern Italy.