PLATYPUS AND ECHIDNA. 



tissue .25 to .5 cm. wide representing the lobus quadratics 

 of the human liver. We have not as in the Platypus the 

 projection of the spigelian lobe ventral to the left lateral 

 lobe. The inner extremity of the left lateral lobe (i.e. at 

 portal interval) is almost pointed. There is a well defined 

 lobus caudatus ventral to the right lateral lobe and more 

 prominent than in the Platypus, so that the greater part 

 of the latter is hidden on this surface, only the upper and 

 outer angle being usually seen. As in the Platypus the 

 caudate lobe has three surfaces — dorsal — ventral for 

 duodenum — and lower or caudal hollowed for the upper 

 pole of the right kidney. In the Echidna more of the 

 concavity for the kidney is formed by the caudate lobe 

 than in the Platypus, in which, half is usually formed by 

 the right lateral and half by the caudate lobe. The right 

 lateral is the larger of the two however, measuring later- 

 ally 8 cm. and dorso-ventrally (> cm., while the caudate 

 measured 5 cm. in each direction. On this surface the 

 right and left portions of the coronal fissure are con- 

 tinued to the portal interval. Here the spigelian lobe is 

 relatively a much smaller structure than in the Platypus 

 and a partial depression or groove between the spigelian 

 and caudate lobes over which passes the portal vein — 

 artery — and common duct constitutes the only distinction 

 between them. The spigelian lobe appears as a somewhat 

 pointed prolongation to the left of the caudate and passes 

 behind the lesser omentum, being contained in the lesser 

 sac and related to the lesser curve of the stomach. In a 

 large male specimen its length was 3 cm. and greatest 

 width 1.75 cm. Passing down in the groove on the dextral 

 extremity of the lateral lobe between it and the spigelian 

 lobe is the oesophagus. On the diaphragmatic surface we 

 described a fold continuous at the inf. v. cava with the 

 suspensory ligament passing vertically at the groove for 

 the oesophagus on the inner margin of the left lateral 



10 



