WOMBAT. ' 



hence the selection value for the passage of the umbilical 

 vein. In some specimens, whilst the fissure is the remains 

 of the old cystic or mesial fissure, the groove may be re- 

 garded as the remains of the dorsal part of the left lateral 

 fissure. This would be the case where the mesial or cystic 

 fissure had failed to reach the portal interval. 



(B) Here the left cystic has fused with the left lateral 

 lobe, and although only a faint impression remains be- 

 tween the two, yet dorsally the remains of the old left 

 lateral fissure is more clearly defined, curving on to the 

 right edge of the left lateral lobe. The longitudinal fis- 

 sure separating the cystic from the left lateral lobe is 

 well defined ventrally, but by a groove dorsally, and is 

 the remains of the cystic fissure between the left and 

 intermediate cystic lobes. 



(C) Here, although the left lateral fissure is well de- 

 fined, and measures 4 cm., yet it does not reach the portal 

 interval, as there is commencing fusion dorsally of the left 

 cystic and left lat. lobes, but the cystic fissure between the 

 intermediate and left cystic lobes is continued as a groove 

 between the left lateral lobe and the narrow dorsal part 

 of the intermediate cystic lobe. 



(D) Here the left cystic has fused with the left 

 lateral lobe, leaving a well defined groove, representing 

 the old left lat. fissure. Between the cystic and left lat. 

 lobes is a fissure ventrally 1.5 cm. long, continued dor- 

 sally as a well defined groove— longitudinal fissure — and 

 is the remains of the mesial or cystic fissure between the 

 original intermediate and left cystic lobes. Into this the 

 groove representing the old left lateral fissure ends, so 

 that there was no question of its dorsal part being the 

 dorsal portion of the longitudinal fissure. 



49 e 



