Section 9. 



BIOLOGY. 



President ov the Section : 



W. BALDWIN SPENCER, M.A., Professor of Biology in the 

 Univc/rsity of Melbourne. 



l.-ON THE ORIGIN OF THE STRUTHIOUS BIRDS 

 OF AUSTRALASIA. 



By F. W. HUTTON, F.R.S., Professor of Bioloc/y in the University, 

 Christchurch, New Zealand. 



The Struthious birds, or Matitcs, are confined to the Southern 

 Hemisphere, with the single exception of the ostrich, which 

 ranges through North Africa into Arabia, and formerly into 

 Central Asia. They exhibit, however, greater variety of 

 form in Australasia than elsewhere, and a few hundred years 

 ago, before the moas were exterminated, this difference was 

 still more marked. Mr. A, R. Wallace's explanation of this 

 remarkable distribution is that the group originated in the 

 Northern Hemisphere in the Cretaceous period, migrated 

 southwards, and became extinct in the Northern Hemisphere. 

 (" Geographical Distribution of Animals," vol. i., pp. 287 and 

 461, vol. ii., p. 370; "Island Life," p. 451.) This opinion 

 is founded on paleeontological evidence. In the Older 

 Pliocene rocks of the sub-Himalaya the remains of an ostrich 

 and of another genus — Hypelornis — supposed to be closely 

 allied to the cassowary, have been found. No Ratitre are 

 known in the Miocene, but in the Lower Eocene of Europe 

 and North America remains of GastoTuis, Dasornis, Meiiri- 

 ornis, and Diatryma occur, which are united — perhaps with 

 some other forms — into a family called Gastoy-nithida; gene- 

 rally supposed to represent the earliest Ratite birds. In the 

 Middle Cretaceous period all the known birds were very 

 different from living ones, and although flying birds and 

 flightless birds existed even then, the flightless birds were 

 adapted for swimming, while the Haiitce are specially adapted 

 for a terrestrial life. It is true that Hesperornis had a skull 



