The Corinthian vases are not, however, strictly homogeneous, and, in fact, fall into certain distinct categories. The earliest class found at Corinth stands quite by itself, and has been termed “Proto-Corinthian,” though the justice of this title has been strongly combated by some scholars. On many of the Sicilian and Italian sites a class of small vases[1012] is found which differs from the authentic Corinthian examples of the same forms, and may not impossibly denote local fabrics. If this is so, they would stand in the same relation to the genuine Corinthian as the Boeotian Geometrical vases to those of the Dipylon, forming a sort of supplementary fabric. At all events, such imitations of a popular ware might reasonably be expected. M. Pottier maintains that five distinct varieties of clay may be observed, which partially serve as a basis for classification, apart from questions of style and ornamentation. They are as follows: (1) small vases of a greenish-yellow clay found in Greece, especially at Corinth, but rare in Italy; (2) vases of cream-coloured clay from Boeotia, and large kraters from Cervetri; (3) vases of reddish clay from Boeotia, Euboea, and Etruria; (4) vases of white and grey clay, very numerous in Italy; (5) vases of yellow clay, chiefly found in Italy. Some of the “Proto-Corinthian” wares belong to Class (1), but as a rule they are marked off from the rest by technique as well as decoration. This first class is without doubt exclusively local, and represents the κέραμος Κορίνθιος of Pollux; the same clay is even used at Corinth at the present day. On one of the Penteskuphia pinakes (see p. 316), the clay of which differs from the rest, a potter is represented making an aryballos of “Proto-Corinthian” form[1013]; but the majority belong to the second class, which is also local, and includes the large kraters of advanced style with Corinthian inscriptions. In colour and porosity the clay resembles that of Boeotia. The red clay of Class (3) suggests a connection with Chalkis, a question which needs future consideration (see below, p. 321); (4) and (5) present analogies to the native clays of Italy, and include all the local imitative fabrics. The older varieties with merely linear decoration are most largely found at Corinth and Syracuse, and the later with incised lines and figures of animals or men are comparatively rare. But as far as the present state of our knowledge permits, it is certainly possible to claim as Corinthian, at least in a sense, all the varieties of fabrics which have been hitherto mentioned, except probably the “Proto-Corinthian.” In describing these fabrics in detail, it will be found more convenient to ignore the technical differences, and adopt the more chronologically accurate system of classification which follows the development of the decoration. We thus obtain five distinct classes,[1014] which may be summarised as follows:—