The mesenteries of many Anthozoa are usually regarded as being arranged in pairs, the members of a pair being adjacent mesenteries. The common shore Anemones, belonging to the Hexactiniæ, show this arrangement very well. In a typical case, the mouth and stomodæum are elongated, and the pairs of mesenteries are arranged in multiples of six. There are six primary pairs passing from the body-wall to the stomodæum, which are complete; six secondary pairs, which may also reach the stomodæum ; twelve pairs of a third series, which are not complete; forty-eight incomplete pairs of a fourth series, and so on.