262 Proceedings of the Royal Physical Society. 
The trachea bifurcates into right and left bronchi and each of these has 
several secondary pockets. The right lung is slightly larger than the left 
as is the case in the adult, according to Pouchet. 
The oesophagus is continued into the stomach, a dilatation of the tube, 
and the gut then runs straight from stomach to anus, except for a loop into 
the umbilical coelome.. It opens into the cloaca which is still separated 
from the exterior by a plug of tissue. The post-anal gut extends almost to~ 
the tip of the tail and there ends blindly. 
The liver is very large and consists of a network of cells, the interspaces 
being filled with blood. Just before the bile duct enters the intestine, 
it gives off a long glandular pocket with one large duct and _ several 
small acini. In the adult, according to Pouchet, the gall bladder is 
embedded in the pancreas. The glandular mass round the main lumen is 
probably pancreatic. There is no sign of any other pancreatic rudiment. 
There is a well-defined mesonephros present extending from about the 
level of the fore limbs to that of the hind limbs. The tubules have lost 
their segmental character and are crowded together, two approximately 
corresponding to each spinal ganglion. The tubules lie close to the posterior 
cardinal vein, have a typical S-shape, and open into the Wolffian duct. At 
the headward end the structure of the tubules is simpler and they are more 
crowded together. On the right hand side there is an isolated simple tubule. 
in front of the end of the Wolffian duct. This perhaps indicates a shifting 
back of the kidney in accordance with its ultimate position. The beginning 
of the ureter on each side is just recognisable as a swelling on the Wolffian 
duct before it enters the widely expanded cloaca. From this there extends 
forward a mass of condensed tissue. There are no secondary tubules 
present. 
The allantois is much expanded before its entrance into the cloaca but 
thins out before leaving the body wall. Its cavity, enclosed in a wall 
containing a network of small blood-vessels, extends for some distance down 
the umbilical cord but does not reach the placenta. The blood-vessels, 
apart from the main allantoic arteries which pass onwards to the placenta, 
die out at the same level. 
The genital ridge is present as a slight thickening of the coelomic 
epithelium below the mesonephros. Farther tailwards this ridge is shifted 
in position, and comes to lie on the root of the mesentery. | pea E 
The coelomic cavities are not yet completely separated off. The pleural 
cavities open widely into the peritoneal cavity. The left pleural cavity is 
connected with the pericardiac cavity by a narrow canal, while the right has 4 
a wide opening. : 
