PLATYPUS AND ECHIDNA. 



lateral from the cystic lobes. Or we may have the dorsal 

 part of the fossa hading into a fissure lodging the duct 

 which is partly between the right and left cystic lobes 

 and partly in the portal interval. The portal interval 

 lies between the narrow inner extremities of the right and 

 left lateral lobes where the coronal and cystic fissures 

 meet. Here the hepatic ducts join the cystic, and it may 

 almost he regarded as the central point of the liver: be- 

 tween the lobus spigellii and the caudate lobe is a depres- 

 sion 1.75 cm. long, often fissured dorsally. 



Here we have passing eaudally the portal vein, com- 

 mon duet, and hepatic artery — the vein lying dorsally as 

 in the human liver. The vena cava passes obliquely up and 

 to the left in the liver substance behind the junction of 

 the right lateral and spigelian lobes to the diaphragmatic 

 surface. The membrane which we described curving 

 round witli the oesophagus from the diaphragmatic sur- 

 face is continued as the gastro-hepatic omentum which is 

 traced on the inner or right part of the visceral surface of 

 the left lateral lobe to the portal interval. This repre- 

 sents the hepatic attachment of the lesser omentum. It 

 is worthy of note that on the left lobe towards the outer 

 boundary an oblique depression may be seen probably 

 indicating the remains of a fissure between two divisions 

 of the left lateral lobe, and a fissure or depression is 

 sometimes noted towards the inner side of this lobe also. 



(b) Echidna. — The mesial, right and left lateral, spi- 

 gelian, and caudate lobes, are defined — as in the Platypus. 

 The suspensory ligament is traced over the ventral edge 

 from the diaphragmatic surface. There may or may not 

 be a fissure where it crosses the ventral edge. It runs on 

 the ventral surface for about .75 cm. and usually termi- 

 nates in a fissure. Between the fundus of the gall bladder 

 and the ligament there is usually a small area of hepatic 



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