PLATYPUS AND ECHIDNA. 



layers of the niesoduodeimm, and as this is free so the 

 pancreas is quite movable on the right side. It is more 

 abundant below the relation of the colon to the meso- 

 duodenum than above it and strands are found to extend 

 along the common bile duct as far as the portal interval, 

 but it does not extend in the gastro-hepatic omentum to 

 the left of the duct, as in the Echidna. Except about the 

 entrance of the ducts there is frequently a distinct in- 

 terval in the mesoduodenum between the pancreas and the 

 duodenum. From the duodenal portion of the pancreas 

 a process is noted passing up and to the left in the lesser 

 sac, i.e., in relation with the great omentum, towards the 

 pylorus. Apart from the process the pancreas is traced 

 to the left in relationship with the colon lying at first 

 in the wall of the lesser sac for about 2-4 cm. and then 

 outside the sac it diffuses itself on the left aspect of the 

 mesocolon, coming into relationship with the fold con- 

 necting the left posterior smaller process of the spleen 

 with the mesocolon of the descending part of the left 

 colon. As stated, the pancreas at its termination forms 

 a someAvhat compact mass, and approaches close to the 

 left pelvic brim. It is important to note that there is no 

 pancreas in relationship either with the body of the spleen 

 nor with the greater right anterior process, both of which 

 are in relationship with the great omentum, being con- 

 tained in the lesser sac. 



Portal Vein. — Two main branches are given oft' — 

 right and left lateral — the former, which first arises, 

 sending a branch to the caudate. On the left side, in ad- 

 dition, two small branches are noted to the spigelian lobe, 

 one from the main trunk and the other from the com- 

 mencement of the left lateral trunk. Finally, the main 

 portal trunk divides into two terminal branches, one to 

 the right mesial and the other to the left mesial lobe. 



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