ds cephalad until it lies laterad to the middle region of the
duodenum, then bends through 180 deg. and extends, in an almost straight
line, to the cloaca, _cl_, lying in the region of the posterior
appendage, _pa_.

The allantois, _al_, extends cephalad for some distance from the floor
of the cloaca. Some distance caudad to the cloaca, near the end of the
much coiled tail, is seen the post-anal gut, _pag_. This structure as
has been noted above, is quite distinct from the other parts of the
enteron. It is of elongated, pyriform outline, with the pointed end
extending cephalad.

In the narrow space between the stomach and the duodenum is the
elongated pancreas, _pan_, opening by two or more short ducts into the
duodenum.

The liver, _li_, in the figure under discussion, has about twice the
area of the stomach. It extends caudad and dorsal about the same
distance as the latter organ, but it extends ventrad and cephalad far
beyond the boundaries of the stomach.

Extending along the ventral border of the liver is a long narrow duct,
apparently the bile duct, _bd_. It connects, caudally, with the anterior
end of the pancreas, while at its other extremity, near the
antero-ventral corner of the liver; it ends blindly.

The transverse sections now to be described have been selected from the
series from which the reconstruction, just described, was made.

Figure 6B represents a typical section through the pharynx. Its plane is
approximately shown by the line 400 of figure 6A though the plane
apparently does not cut the eye, _e_. The pharynx, _ph_, has here the
outline of an irregular V. Its walls, except at the outer angles of the
clefts, _g^1_, are composed of but a single layer of cells. In the
dorsal wall these cells are flattened, while in the ventral wall they
are more rounded. This difference in the shape of the cells accounts for
the slightly greater thickness of the floor over that of the roof of the
pharynx. The gill clefts no longer communicate with the exterior.

Figure 6C represents the caudal half of the embryo in the plane 475 of
figure 6A. The section of the pharynx, _ph_, is here crescentic in
outline, and the pharyngeal walls, especially the floor, are somewhat
thicker than in the more anterior section just described. Lying a short
distance dorsad to the pharynx are seen two small, thick-walled
openings, _ty_; these are the rudiments of the thymus glands. They are
here quite distinct from the enteron, a