Passing over a list of similar objects, we finally come to the world-famed terra cotta heads. Like the other terra cotta objects, these are fully illustrated in the above-named work. They are of "infinite variety" and "every observer may well see that they are patently portraits." They represent many varieties of Central Africans, from the restricted minority group of prognathous flat-nosed, thick-lipped type of the coast to the more delicate and sharper featured types to which the majority of Africans belong. In other words, these terra cottas represent almost every African type suggesting, therefore, a civil life very cosmopolitan in character and the probable existence of a _jus commercii_ as well as a _jus connubii_, which in turn argues well for the existence of a demogenic form of association of a very great age. Frobenius testifies that these heads are of "great beauty and amazing to those who inspect them." Commenting upon these terra cottas in general, he says: "I do not think that there can be the least doubt but that we are faced with a local form of art whose perfection is absolutely astounding," and commenting upon one particular head which he calls _mia_ after the native term for it, he concludes that it "must be regarded as the most important object hitherto found on African ground and as the finest work of art so far discovered outside the narrow Nile valley, on the further side of the old Roman jurisdiction."[39] We may now turn for a brief study of what is beyond all doubt the most important division of the whole group of African arts and crafts--the metal castings. As was mentioned in the Introduction, the conquest of the city of Benin by the British in 1897 opened up to the knowledge of the white world a hitherto unknown field of Negro art, "the productions of which," according to Ling Roth, "will hold their own among some of the finest specimens of antiquity or modern times."[40] The excavations of Frobenius's expedition discovered in the heart of this part of Negro-land, aside from the terra cottas already described, metal works which are characterized as being "indeed like the finest Roman examples."[41]