PLATYPUS AND ECHIDNA. 



lobe. This becomes continuous with the hepatic attach- 

 ment of the gastro-hepatic omentum which runs along 

 the ventral surfaces of the narrow inner part of the left 

 lateral lobe to the portal interval. On the inner side of 

 the left lateral lobe a small lobe may be separated off by 

 a fissure. On the caudal or renal aspect the inf. v. cava 

 can be seen passing between the spigelian and caudate 

 lobes but is not visible in its hepatic relation from this 

 aspect. The left lateral measures 5-6 cm. laterally and 

 the complete cystic 6 cm. The ventral surface of the 

 left cystic and left lateral lobes are related to the bodv 

 of the stomach. The duodenum is related to the right 

 cystic, right lateral, and caudate lobes. The liver is 

 larger in the Echidna than in the Platypus, its greatest 

 lateral measurement being 16 cm. and dorso- ventral 10-12 

 cm., whilst in the Platypus the length laterally may reach 

 13 cm. and dorso-ventrally 8-9 cm. 



Gall Bladder and Ducts, 



(a) Platypus.- — The (Jail Bladder is smaller than in 

 the Echidna and projects at the ventral margin of the 

 mesial or cystic lobe. It is usually empty and collapsed, 

 unlike that of Echidna, and measures 2 cm. long and 1-1.5 

 cm. wide ventrally. It is a somewhat pear-shaped struc- 

 ture presenting a fundus or ventral extremity and body. 

 Though the fundus is mobile the gall bladder is really a 

 fixed organ, being invested by peritoneum on the sides 

 and under or ventral surface only. At the exit of the 

 cystic duct it usually narrows somewhat, so that a neck 

 may be described. On the other hand the duct may pass 

 abruptly from the body. 



Cystic JHtcf.- -This measures 1 cm. long. It may lie 

 partly between the right and left portions of the cystic 

 or mesial lobe and partly in the portal interval, or it may 



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