PLATYPUS AND ECHIDNA. 



Visceral Surface. — (a) Platypus.— The three main 

 divisions are seen to be present, viz., mesial or cystic 

 separated by the gall bladder into a right and 

 left portion, and the right and left lateral Lobes. The 

 under surface of the left lateral is free from projection, 

 but from the right lateral we have projecting the lobus 

 spigelii and dextrally the larger free caudate lobe. The 

 caudate lobe is hollowed below, forming with the right 

 lobe a concavity for the reception of the convex upper 

 part of the kidney. Its ventral surface is related to the 

 mesoduodennm, pancreas, and colon. It measures 4.5 cm. 

 laterally and 3 cm. dorso-ventrally. The spigelian lobe is 

 seen to lie below the under surface of the left lobe, from 

 which it is free however and projects into the lesser 

 peritoneal sac. It measures 2.3 cm. laterally and 2 cm. 

 in greatest width. On its inner or sinistral surface is a 

 groove corresponding to the pyloric knob and commence- 

 ment of the duodenum, and ventral ly it is related to the 

 duodenum as far out as the duct. The right lateral lobe 

 like the caudate has three surfaces — diaphragmatic — - 

 lower or caudal to receive with the caudate the upper pole 

 of the right kidney — and the visceral. This latter is re- 

 lated to the duodenum which is lodged in a depression 

 with a ridge internally. It curves along the outer part of 

 the right cystic — right lateral - and occasionally 

 the caudate. The gall bladder is placed on the 

 under surface of the mesial or cystic lobe. Where 

 a fissure exists on the diaphragmatic surface we 

 have on this aspect also a fissure lodging the gall blad- 

 der, and the cystic lobes on each side are of equal size. 

 Usually however the gall bladder is lodged in a fossa 

 which encroaches more on the visceral surface of the right 

 cystic than the left cystic lobe. The cystic duct may not 

 be related to the cystic lobe — the gall bladder extending 

 to the coronal fissure which separates the right and left 



