OF THE KOALA AND VULPINE PHALANGER. 



575 



a fine nerve (F), whicli enters into the foriTiation of the aortic 

 plexus fai-ther back (G). Fine fibres (H) connect the halves of 

 the plexus. 



Branches of distrihiUion : — 



1. Three nerves which coui'se along the postcaval vein and 

 embrace the right suprarenal capsule (1). 



2. Hepatic plexus (J). 



3. Splenic plexus (K). 



4. Right renal plexus (L). 



5. Two cords (M and N) which emerge from the posterior end 

 of the right half of the plexus and form a loop lying dorsal to the 

 postcaval vein. The left one breajis up into a number of fibres 

 which reunite later with the right one, and it gives ofi" the left 

 renal plexus (0). 



The loop unites with the left sympathetic by a T-shaped 

 junction (P), and fine filaments (Q, Q, Q, Q) also ran between 

 them. 



Only one cervical sympathetic ganglion — namely the superior 

 one — exists. 



Summary. 



The difierences between Phascolarctos and Tridiosurus may be 

 summarised as follows : — 



Fhascolarctos. 



Plati'sma myoides strong. 



No true hyoglossus muscle. 



Vena transversa A-sliaped. 



Absent. 



Lateral organs of tongue look like 

 glands. 



One vallate papilla. 



Plicfe fimbriatae present. 



Cheek-pouches present. 



All anterior palatal ridges trans- 

 verse. 



Tongue far from epiglottis. 



Epiglottis broad and entire. 



Gland-patcli in stomach. 



Pjdorus projects into the duodenum. 



Tonsils far back in the pliarj-nx. 



Pharynx has two dorsal ridges. 



Absent. 



Cardiac apex obtuse. 



Absent in my specimen. 



Postcava crosses end of abdominal 

 aorta. 



Liver more subdivided. 



Gall-bladder long and narrow. 



Right kidney posterior to liver, and 

 each kidney has one conical papilla. 



Thyroid gland in posterior part of 

 neck. 



Proc, Zool. Soc— 1921, No. 



Tridiosurus. 



1. Platysma weaker. 



2. Hyoglossus present. 



3. Horizontal. 



4. Anterior jugular vein present. 



5. Composed of fissures and laminte. 



6. A vallate triangle. 



7. Sublingua well developed. 



8. Absent. 



9. Anterior palatal ridges convex for- 



wards. 



10. Close to epiglottis. 



11. Narrow and notched. 

 13. Absent. 



13. Pylorus does not project. 



14. Tonsils in fauces. 



15. Absent. 



16. Dorsal ridge in nasal tube. 



17. More acute. 



18. Innominate artery present. 



19. Postcava conceals posterior half of 



aorta. 



21. Short and wide. 



22. Sunk in liver, and each kidney has 



one broad, flat papilla. 



23. In anterior part. 



XXXIX. 



39 



