576 DR. C. p. SONKTAG ON TUE COxMPARATIVE ANATOMY 



Tliascolarctos. 



24. No thyroid isthmus. 



25. Patelhi absent. 



26. Absent. 



27. Two lobes in each lune. 



TricJiosurus. 



24. Isthmus present. 



25. Patella thin and scale-like. 



26. Right lung has an az3'gos lobe. 



27. Left lung has two, and right has 



four lobes. 



28. Spleen has a lateral jjiece. 



28. Spleen triangular, and has no lateral 



process. i 



29. Vertebral arteries arise from sub- 1 29. Vertebral arteries arise from an 



clavian arteries. i axis on each side. 



30. Intestinal measurements much 



greater. [ 



Owen stated that the Koala is the Marsupial which has the 

 greatest claim to typical pre-eminence. MacAlister, on the other 

 hand, showed that it has more individual peculiarities in its 

 myology than has any other Didelphian ; and the remarks made 

 in this paper show how many of the appearances of its internal 

 organs are peculiar to itself, for several of those described for 

 Trichosiirus vulpecula ai-e similar to the conditions present in 

 many Marsupialia. There are also many striking differences 

 between the external and skeletal characters of Fhascolarctos and 

 those of Trichosurus, but I have nothing new to add to existing 

 descriptions. 



Bibliography. 



1. Braus, H. — Jen, Denkschr. Bd. 5 (Semon, Zool. Forschungs- 



reisen, Bd. 2). Jena. G. Fischer, 1896. 



2. Edelmann, T. — Deut. Zeitschr. f. Thiermed. Bd. xv. 



pp. 165-214. 1899. 



3. Flower, W. H. — " The Comparative Anatomy of the Organs 



of Digestion of the Mammalia." Medical Times and 

 Gazette, 1872, p. 645. 



4. Forbes, W. A. — " On some Points in the Anatomy of the 



Koala." Proc. Zool. See. London, 1881, pp. 180-195, 



5. Home, E. — " An Account of some Peculiarities in the 



Anatomical Structure of the Wombat." Phil. Trans. Roy. 

 Soc. 1808, pp. 304-312. 



6. Knox, R. — " On the Wombat of Flinders." Edinburgh New 



Philosophical Journal, vol. i. p. 104. 1826. 



7. MacAlister, A. — " The Muscular Anatomy of the Koala." 



Annals and Magazine of !N"atural History. 1872, pp. 127- 

 134. 



8. Martin, W. — '' Notes on the Anatomy of the Koala." Proc. 



Zool. Soc. London, 1836, pp. 109-113. 



9. Mitchell, P. Chalmers. — " Further Observations on the 



Intestinal Tract of Mammals." P. Z. S. 1916, pp. 195- 

 197. 



10. Oppel, a. — Text-book of Comparative Microscopic Anatomy, 



vol. i. p. 291, and vol. iii. p. 308. 



11. Owen, R.— Art. "Marsupialia" in Todd's ' Cycloptedia of 



Anatomy and Physiology,' vol. iii. 



