1895.] 



AND BRAIN OF DENDEOLAGUS BENNETTI. 



135 



Owen in D. inustus. In the species which forms the subject of the 

 present memoir, the liver formula may be represented on G-arrod's 

 plan thus : — 



L.L. 2>L.C.=E.C. 2>E.L. 3<Cau. 



This formula differs markedly from that of Petrogale penicillata, 

 which is as follows : — 



L.L. 4>L.C.=E.C.<E.L. 3<Cau. 



I am not disposed to think that very much stress can always be 

 laid upon the relative sizes of the lobes of the liver. For example, 

 in two species of Hahnaturus the formulae are as follows : — ■ 



H.hennetti. L.L.<L.C.>E.C, 2>E.L. 3<Cau. 



H.hrachijurus. L.L. 2>L.C. = E.C.=E.L. 2<Cau. (Garrod, 



MS. sketch). 

 On the other hand, the liver of Dendrolagus shows two characters 

 by which it can be distinguished from that of all the above-mentioned 

 species and from Petrogale (fig. 4) and Macropus melanops : — 



(1) The right lateral lobe is not separated by a complete fissure 

 from the caudate. 



(2) The Spigelian lobe is distinctly bilobed. 



Kg. 4. 



Liver of Petrogale ; abdominal surface. 

 Lettering as in fig. 3. 



§ Heart and Vascular System. 



The only point that I noticed in the structure of the heart as 

 compared with that of Petrogale is the presence of four separate 

 papillary muscles attached to the free flap of the right auriculo- 

 ventricular valve, instead of only three. The additional muscle was 

 attached to the free wall of the ventricle. 



