360 



TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



staining alveoli of (3). The parotid gland was of still 

 another type ; three alveoli are represented in (2). All 

 are made up of darkly staining cells, as in the serous 

 alveoli of fig. 3. The nuclei are, however, nearer the 

 external surfaces of the cells. 



The submaxillary gland, therefore, consists of two 

 portions. One of these, a mixed gland, is bound up with 

 the cervical thymus, to form one structure. The other 

 lies underneath, and is a mucous gland. The parotid is a 

 serous gland. 



It may be useful to summarise here what has been 

 made out regarding the presence of this cervical thymus 

 organ in the families of the Marsupialia. Representative 

 genera from all the six families have now been examined 

 by Professor Symington,* and by myself,! and the 

 relationships of thoracic and cervical thymus organs have 

 been ascertained in these forms. The facts may be 

 expressed in the form of a table. 



DlPROTODONTTA. 



Superficial cervical thymus 

 always present. Thoracic thymus 

 usually present, but may be 

 absent. 



Macropodiclce : — 



Macropus bennetti. 



rufus. 



wilcoxii . 



eugenii. 



giganteus. 



rufus. 

 Dendrolagus sp. 



Phalan get idee : — 



Trichosurus vulpecula. 

 Phascolarctus cinereus. 

 Acrobates pygmoeus. 



Phascolomyidce : — 



Phascolomys wombat. 



POLYPROTODONTIA. 



Superficial cervical thymus 

 always absent. Thoracic thymus 

 usually present, but varies as in 

 other mammalia. 



Didclphyidce : — 



Didelphys virginiana. 

 ,, pusilla. 



,, murina. 



Dasyuridce : — 



Dasyurus viverrinus. 

 ,, cancrivora. 

 Thylacinus. 

 Antechinomys lanigera. 



Peramelidce : — 



Perameles gunni. 



* Symington, Jour. Anat. Phys. loc. cit. 

 f Johnstone, Journ. Linnean Soc. London, vol. 26, pp. 537-557. 1898. 



