Figure 17_d_ is in the region of the posterior end of the heart (_ht_), which is cut through the tip of the ventricle, and the anterior end of the liver (_li_), which has the appearance of a mass of darkly stained cords or strands of cells surrounding a large blood-vessel (_mv_). This blood-vessel may be called the _meatus venosus_, though it is not separated by any line of demarcation from the auricle. A few sections anterior to this region the _meatus venosus_ opens dorsally into a large vessel on each side (_dc_), which at first glance seems a part of the body cavity, but which is in reality the _ductus Cuvieri_, formed by the union of the anterior and posterior cardinal veins. An irregular, crescentic cleft (_bc_), lying medial and parallel to each of the Cuvierian vessels, is the body cavity. In the upper angle of this cavity is a granular mass, the glomerulus, that of the left side being accompanied by the extreme anterior end of the Wolffian duct. In the rounded mass of mesoblast, between the cleft-like regions of the body cavity, the lung rudiments (_lu_), and the œsophagus (_oe_) are seen as three small, circular openings; that of the œsophagus is somewhat smaller than the other two. The notochord (_nt_), spinal cord (_sc_), and muscle plates (_mp_) have almost the same appearance as in the preceding section. A spinal ganglion (_sg_) is seen on each side of the spinal cord; the one on the left shows a well-defined spinal nerve (_sn_), which may be traced ventrally as far as the end of the muscle plate, along whose medial side it courses. The ventral nerve root is plainly seen; the dorsal root, in this section, less plainly. The amnion (_a_) and abdominal wall are, as in the preceding figure, torn in the region of the ventricle.