18 POPULAR SCIENCE MONTHLY. 



the Miocene period in the complete supremacy of the placentals and 

 the almost utter extinction of the marsupials in the principal regions 

 of the earth. Of the latter class of animals, the didelphys of the 

 western hemisphere, of which the American opossum is the best- 

 known species, is the sole survival outside of Australia. This is owing 

 to the fact that all the other continents have been more or less closely 

 connected by land during long geological epochs. This is still the 

 case with Europe, Asia, and Africa; even the dividing basin of the 

 Mediterranean is of relatively recent origin, as may be clearly shown 

 by a comparison of the fauna of its northern and southern shores. 

 Also the extreme northern points of America and Asia, although 

 previously separated, were subsequently united for a long time, be- 

 ginning with the latter half of the Tertiary period and extending into 

 the Pleistocene age, when the species of mammals now prevailing 

 in both hemispheres were already existent. It is therefore perfectly 

 intelligible that, under these circumstances, Australia and the adja- 

 cent groups of islands should be of special interest to the naturalist 

 as fields of investigation; for there he can study living specimens 

 of mammals, birds, fishes, and reptiles of which he finds elsewhere 

 only the petrified remains. 



It was with this object in view and with the pecuniary aid de- 

 rived from the Ritter endowment fund that Dr. Richard Semon, 

 a former pupil of Ernst Haeckel, and now professor of anatomy 

 and zoology in the University of Jena, landed at Adelaide in the 

 midsummer of 1891, and pitched his camp in the Burnett district 

 of the Australian bush, at first on the banks of the Boyne River. He 

 engaged as companion and general conductor of the expedition a 

 German immigrant named Dahlke, whose family had left their 

 fatherland when he was only four years old, and who had grown 

 up into a thorough Australian. This man furnished a dray and ^.ve 

 horses as the most convenient means of conveyance, and secured the 

 services of eight families of aborigines, consisting in all of about 

 thirty persons, men, women, and children, whose business it was to 

 catch fish and search the dense Australian scrub for specimens of 

 its fauna. 



In order to stimulate the activity of the natives, Semon offered 

 prizes for the capture of particularly desirable animals, and also 

 promised to pay their regular wages at the end of every week; but 

 a single experience of the results attending the latter part of this 

 arrangement sufficed to prove its utter impracticability; for no 

 sooner did they find themselves with cash in hand on Saturday even- 

 ing than they procured several bottles of rum from a liquor shop 

 kept by an Irish woman several miles distant, and on Sunday morning 

 were all dead drunk. In order to prevent a repetition of this booz- 



