The oesophagus, _oe_, diminishes slightly in caliber for a short distance caudad to the origin of the lungs, then gradually increases in caliber until it suddenly bends to the side (towards the observer) and merges into the wide stomach, _i'_. The stomach, which is irregularly conical in shape, lies in a place slightly nearer the observer than the end of the lung rudiment mentioned above. Lying to one side of the stomach and duodenum, and extending cephalad beyond the end of the lung rudiment is the liver, _li_, whose outline is only roughly shown here by the broken line. The stomach opens rather abruptly into the duodenum, _d_, which slopes back towards the plane of the oesophagus (away from the observer). The projection from the side of the duodenum, _pan_, not well figured here, indicates the position of the pancreas, better shown in the next reconstruction. The duodenum extends only a short distance caudad to this point and then opens, _aip_, to the yolk-sac. The yolk-stalk, or unclosed region of the enteron, is still of considerable extent, though its exact boundaries are not easy to determine. The distance between the anterior and posterior intestinal portals is approximately shown in the figure under discussion. The hindgut is cylindrical in cross section and of about the same diameter throughout, except for a slight enlargement in the cloacal region. The post-anal gut is not shown here; it will be described in connection with the next reconstruction where it is figured. Figure 6 is a surface view in profile of an embryo of the next stage to be studied. The manus and pes are here well developed, and the general development of the embryo is in considerable advancement over the last stage studied. Figure 6A represents a reconstruction, from a series of transverse sections, of the enteron of an embryo of about the age of the one shown in figure 6. The outlines of the entire embryo, of the eye, _e_, and of the anterior, _aa_, and posterior, _pa_, appendages are shown by broken lines. Its position being coincident with that of the stomach, liver, and pancreas, the anterior appendage can scarcely be seen. The enteron, including one lung only, for the sake of simplicity, is shaded solid black, while the liver and pancreas, with their ducts, are outlines with unbroken lines. As in the preceding reconstruction no attempt is made to show the gill clefts, and only the dorso-ventral profile of the enteron is shown. Caudad to the pharynx, the enteron being more or less cylindrical in section, this profile gives a good idea of its shape, but in the pharyngeal region, where the lateral diameter is so much greater than the dorso-ventral, the reconstruction gives but a poor idea of the size of that part of the enteron. The widely-open mouth, _m_, leads, with no line of demarkation, into the pharynx, _ph_, which is of irregular outline and, as has been said, of much greater lateral than dorso-ventral diameter.