Above the strata, however, which contain these remains of local divergent development, there lies in all districts of the Ægean area a rich layer of deposit, whose contents show a rapid and marked advance in civilisation, are essentially uniform, and have only subsidiary characteristics due to local influence or tradition. The civilisation there represented is not of an origin foreign to the area. The germs of all its characteristic fabrics, forms, and motives of decoration exist in the underlying strata, though not equally in all districts, and the change which Mycenæan art occasions is not always equally abrupt. It is most reasonable to see in these remains the result of the action of some accidental influence which greatly increased the wealth and capacity of one locality in the area, and caused it to impose its rapidly developing culture on all the rest. The measure of the reaction that took place in divers localities thereafter depended naturally on the point to which local civilisations had respectively advanced in the pre-Mycenæan period. As to the decorative motives in vogue, there is less uniformity. The earlier Mycenæan vessels have curvilinear and generally spiraliform geometric schemes. These pass into naturalistic vegetable forms, and finally become in the finest typical vases almost exclusively marine--_algæ_, octopods, molluscs, shells, in many combinations. Everywhere animal, bird, and human forms are but seldom found. Man certainly appears very late, and in company with the oriental motives which characterise the Spata objects. Insects, especially butterflies, become common, and when their antennæ terminate in exquisite spirals, decorative art is at the end of its progress. [Illustration: SILVER OX-HEAD FROM MYCENÆ] Not only in the continuous and universal commentary of painted earthenware, but in many other media, we have evidence of “Mycenæan” art, but varying in character according to the local abundance or variety of particular materials. We have reached an age when the artist had at his disposal not only terra-cotta, hard and soft stone, and wood, but much metal, gold, silver, lead, copper, bronze containing about twelve per cent. of tin alloy, as well as bone and ivory, and various compositions from soft lime plaster up to opaque glass. If it were not for the magnificent stone utensils, in the guise of lioness heads, triton shells, palm and lotus capitals, with spirals in relief, miniature shields for handles, which have come to light at Knossos, we should have supposed stone to be a material used (except architecturally) only for such rude metallic-seeming reliefs as stood over the Mycenæ gate and circle graves, or for heavy commonplace vases and lamps.