My colleague, Robert Adams, believes that there were certainly riverine-adapted food-collectors living in lower Mesopotamia. The presence of such would explain why the Eridu assemblage is not simply the sum of the Halafian and Samarran assemblages. But the domesticated plants and animals and the basic ways of food-production must have come from the hilly-flanks country in the north. Above the basal Eridu levels, and at a number of other sites in the south, comes a full-fledged assemblage called Ubaid. Incidentally, there is an aspect of the Ubaidian assemblage in the north as well. It seems to move into place before the Halaf manifestation is finished, and to blend with it. The Ubaidian assemblage in the south is by far the more spectacular. The development of the temple has been traced at Eridu from a simple little structure to a monumental building some 62 feet long, with a pilaster-decorated façade and an altar in its central chamber. There is painted Ubaidian pottery, but the style is hurried and somewhat careless and gives the _impression_ of having been a cheap mass-production means of decoration when compared with the carefully drafted styles of Samarra and Halaf. The Ubaidian people made other items of baked clay: sickles and axes of very hard-baked clay are found. The northern Ubaidian sites have yielded tools of copper, but metal tools of unquestionable Ubaidian find-spots are not yet available from the south. Clay figurines of human beings with monstrous turtle-like faces are another item in the southern Ubaidian assemblage. [Illustration: SKETCH OF SELECTED ITEMS OF UBAIDIAN ASSEMBLAGE] There is a large Ubaid cemetery at Eridu, much of it still awaiting excavation. The few skeletons so far tentatively studied reveal a completely modern type of “Mediterraneanoid”; the individuals whom the skeletons represent would undoubtedly blend perfectly into the modern population of southern Iraq. What the Ubaidian assemblage says to us is that these people had already adapted themselves and their culture to the peculiar riverine environment of classic southern Mesopotamia. For example, hard-baked clay axes will chop bundles of reeds very well, or help a mason dress his unbaked mud bricks, and there were only a few soft and pithy species of trees available. The Ubaidian levels of Eridu yield quantities of date pits; that excellent and characteristically Iraqi fruit was already in use. The excavators also found the clay model of a ship, with the stepping-point for a mast, so that Sinbad the Sailor must have had his antecedents as early as the time of Ubaid. The bones of fish, which must have flourished in the larger canals as well as in the rivers, are common in the Ubaidian levels and thereafter. THE UBAIDIAN ACHIEVEMENT