OBSERVATIONS. 



cava and the caudate lobe of the early human foetus the 

 additional placental circulation must be borne in mind. 

 Furthermore, in the more primitive livers, the caudate 

 lobe is to a large extent an accommodation effect for the 

 upper pole of the right kidney, as is seen in the Echidna. 

 With, however, the comparative fixation of the duodenum 

 and pancreas, and unification of the organ, a more limited 

 relation of the kidney to the liver is seen. 



The spigelian lobe is well defined in the Monotremes, 

 but reaches its maximum in the Macropodida?. It is poorly 

 developed in the remaining Marsupials, and in the Wom- 

 bat it may be regarded as non-existent. In the Platypus 

 its definition is associated with four factors: — 



(a) Ventral to it lies the lesser omentum. 



(b) On the left side, looping round it, are the 



oesophagus — p c yloric knob — and commence- 

 ment of duodenum. 



(c) Behind lies the inf. vena cava, in its hepatic 



relationship, which is dorsal. 



(d) On its right we see the portal vein, artery, and 



duet, in a well defined depression between it 

 and the caudate lobe. 



In Macropus we have the large spigelian lobe dipping 

 down within the lesser sac in the interval between the 

 right and left portions of its great stomach. In relation 

 with this is a large abdominal oesophagus, frequently 

 reaching 10 to 12 cm. in length. Defining it on the right 

 we see the inf. v. cava, ventral to which lies the portal 

 vein, artery, and bile duet. In neither Koala nor Wom- 

 bat is there an abdominal oesophagus. According to the 

 late Professor Cunningham, an abdominal oesophagus of 

 varying length can usually be described in the human sub- 



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