Glass vessels of the Roman period found in Spain are similar in form and manufacture to those which we know were made in France and Italy. This is not to be wondered at, if we remember that the Romans imposed their artistic forms on the countries they conquered. It is impossible to classify the specimens of this industry into determined localities. The study of the glass paste may, at some future period, give materials for such a classification. One special characteristic of Roman glass may be taken into account to be applied to Spanish glass of a later period. We find ancient specimens constantly ornamented with a sort of thread or line which runs all over the vase. These lines are sometimes made of transparent glass, and sometimes of white opaque glass, termed in Italy _latticinio_ from its milky whiteness. When the industry of glass making was revived in Europe during the fifteenth and sixteenth centuries, classical forms were copied in this as in other industries; this line ornamentation was copied on a much smaller scale in Italy than in Spain, where it constituted the chief and constant characteristic of glass making. It is an interesting fact that objects of a traditional Moorish form have the greatest amount of lines of this style of ornamentation. We cannot, until this subject is more thoroughly investigated, do otherwise than infer either that the tradition of this industry was preserved in Spain, or that the Arabs imported this style of decoration from the same localities from which it had been copied by the Romans centuries before. The comparison of these different styles of glass making can be carried out in a most satisfactory manner in London by examining the fine specimens of glass in the British Museum (Slade collection), and the old Spanish glass at South Kensington. We have no specimens of glass of the Visigothic period. If, as is most probable, glass was used by the Visigoths, they may have imported it from the East, for the text I have quoted from the works of St. Isidore seems to prove that this industry had ceased to exist in his time. The glass paste of different colours must, however, be mentioned, which is set in gold in the Visigothic crowns found at Guarrazar, near Toledo. It imitates precious stones, and was very generally used during the Byzantine period; its occurrence here makes it appear probable that at any rate the tradition of this industry existed in Spain. From the 8th to the end of the 15th century, during the Mahomedan domination, I infer that the industry of glass making became as important in Spain as that of pottery. No specimens, however, of the earlier period have reached us, and we must judge of what it was from the glass vessels in the Kensington Museum, belonging to the Renaissance period, which preserve their Oriental form, and are of a different style to that of Venice and other localities in Europe.