870 £>R. C. F, SONNTAG ON THE VISCERAL ANATOMY 



In Perameles obesula (text-fig. 76 G) the spleen has a massive 

 triangular body with thick sides, and the angles are prolonged by 

 cylindrical or flattened processes of splenic tissue. If the pro- 

 cesses are removed, the resulting organ resembles that of 

 Phascolomys described and figured by Colin Mackenzie. Garrod 

 states in a hitherto unpublished note that the spleen of the 

 Wombat forms an equilateral triangle. In a specimen of 

 Phascolomys mitchelli it had a lateral piece. In Perameles nasuta, 

 it is thin and triangular, without prolongations. 



The Bandicoots are the only Marsupials in which I observed 

 a continuity between the splenic and duodenal peritoneal liga- 

 ments. And the looseness of connection between the spleen and 

 stomach differs considei-ably ; these viscera were very closely 

 united to one another in Dendrolagus ursinws. 



Osgood (9) showed that the spleen of Coenolestes obscurus has 

 an elongated body and a lateral piece, so it differs from that of 

 Perameles obesula. 



In Metachirus opossimi it is T-shaped, with one of the hori- 

 zontal limbs short (text-fig. 76 H). 



The external appearances of the spleens difier considerably 

 even in different species. Histological examination of the spleens 

 of many Marsupials shows that there is a very strong trabecular 

 network. 



The Respiratory Organs. 



The epiglottis is large, and its apex, which is entire or notched, 

 is frequently emarginate. It lies vertically or inclined forwards, 

 and it is sometimes gripped by the posterior extremity of the 

 nasal tube. And it is closely related to the base of the tongue in 

 all Marsupials except Phascolarctos cinereus. As the form of the 

 epiglottis and prominence of the aryteno-epiglottic folds vary, 

 the shape and size of the superior aperture of the larynx differ 

 considerably (text-fig. 77). 



In Didelphys azarce the epiglottis is large, conical, connected 

 to the arytenoids by prominent ligaments, and strongly emar- 

 ginate, without any trace of a notch. The superior aperture of 

 the larynx is long and narrow, and cuts into the posterior surface 

 of the epiglottis. In D. mai^supialis, on the other hand, the 

 entire epiglottis is only slightly emarginate, the arytenoid carti- 

 lages are plainly visible, and the superior laryngeal aperture is 

 wide and round. In Philander laniger and Marmosa elegans the 

 epiglottis is broad, and its apical margin is slightly concave but 

 not emarginate ; and the superior aperture of the larynx is 

 triangvilar. Their condition is intermediate between those of 

 Didelphys and Metachirus opossum, in which the non-emarginate 

 apex of the epiglottis is notched. The epiglottis, therefore, 

 is of considerable value for differentiating the genera of the 

 Didelphyidse from one another. 



The epiglottis is large, prominent, and entire in the Dasyuridse. 

 In Dasyurns viverrinus it is uniformly thick and the apex is 



