17fi PHYSIOLOGICAL SERIES. 



the Macropodidro. There is a typically complete hippo- 

 campal arc of the usual Marsupial type, but its dorsal part 

 is hidden by a great pallial operculum which descends as 

 tar as the dorsal commissure, so as to produce a spurious 

 resemblance to the Eutherian condition. Such a neopallial 

 operculum is found in all large Marsupials, such, tor in- 

 stance, as the Thylacine. In the right hemisphere this 

 pallial opcMVulum has been removed by dissection (fig. f)f>). 

 and the fascia dentata is thus seen to extend far forward 

 above and beyond the dorsal commissure, just as it does in 

 the Tasmanian Devil (D. 197) and in all Marsupials. The 

 arrangement of the hippocampus in the ventricle may 



Fig. 56. (Nat. size.) 



COMM.D. FASC DENT. 



SULC.CALC. 



thus be correlated with the distribution of its specialised 

 fringe ( fasria dentata) in the mesial wall of the hemisphere. 



Above the upturned caudal extremity of the rliinal 

 fissure a deep calcarine sulcus is found : it is prolonged 

 obliquely upward and forward for a short distance so as to 

 converge with an anterior oblique sulcus toward the dorsil 

 edge of the hemisphere. This anterior oblique sulcu- i- 

 a pparently analogous to the genual sulcus of other mam- 

 malian orders. Immediately in front of the genual sulcus 

 and the anterior extremity of the hippocampal fissure there 

 is a short rostral sulcus extending obliquely upward and 

 slightly forward. On the right side it bifurcate- and 

 become- Y->haped. 



There i> a deep and typically -bent rhinal fissure. From 

 the neighbourhood of the, angle of this fissure on the left 

 hemisphere three sulci diverge widely in the neopallium. 



