There is no external indication of an oesophageal valve. It can,however, be readily demonstrated by pulling the oesophagus forward from the mesenteron. This action will pull from within the mesenteron an extension of the oesophagus. This extension of the oesophagus into, and for a distance of one-third the length of the mesenteron, is the oesophageal valve (Plate III, Fig. 5). Just at the point of entry of the oesophagus into the mid-gut, gross dissection reveals six splinter-like fingers of chitin. These chitinous structures are light brown in color, and run along the longitudinal axis of the alimentary tract almost to the end of the extension of the oesophagus into the mesenteron. A microscopical examination of a cross section shows these chitinous fingers to be located on the interior surface of the intima (Plate III, Fig. 6). These pieces of chitin remain unstained in mounted serial sections, and are not united at any point but are attached to, or embedded in, the layer of intima. R. T. Everly, in his study of the Margined Blister Beetle, found only four such structures. He also found that they were attached anteriorly only and were free and separate posteriorly.