228 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



cases, however, the growth changes are retarded and one individual 

 caused much perplexity as it is 20 mm long and still reveals only single 

 pores in the petals and hence was regarded as a new species of Palaeotropus. 

 But the discovery of intermediate stages, showing all steps from poreless 

 plates to normal twin-pored petals has been convincing in the demonstra- 

 tion of this striking example of stages in development, so ably presented 

 by Jackson (1899). 



For the opportunity to study this extraordinary collection, the writer 

 is greatly indebted to Chancellor R. B. von KleinSmid of The University 

 of Southern California and to Captain Allan Hancock and Professor 

 Irene AlcCulloch of the Allan Hancock Foundation. Lieutenant Com- 

 mander Fred C. Ziesenhenne, who played a major part in the collecting, 

 preserving and arranging of the material, deserves high praise for the 

 quality of his work. For thp pleasure of being his co-worker in the 1938 

 cruise of the Velero IIIj I am deeply indebted to Captain Hancock. That 

 was one of life's great experiences and words are quite inadequate to 

 express my appreciation. Finally I take pleasure in acknowledging the 

 very great debt I owe to Mrs. Ora Willett for her patient assistance in 

 the study of the collection and in the pi'eparation of the manuscript — 

 assistance for which these few words of appreciation are quite inadequate. 



