XVIL-THE PTEBOBRANCHIA OF THE SCOTTISH 

 NATIONAL ANTARCTIC EXPEDITION. 



BY S. F. HARMER, Sc.D., F.R.S., Keeper of the Department of Zoology in the British 

 Museum; and W. G. RIDEWOOD, D.Sc., Lecturer on Biology in the Medical 

 School of St Mary's Hospital, University of London. 



(WITH FIVE TEXT FIGURES AND TWO PLATES.) 



