488 University of California Publications in Zoologjj [Vol. 18 



(1916, part V) and of Miyagawa (1916) have been translated for me 

 by F. T. Konno, a Japanese student in the University of California. 

 It has been from this translation, from the reviews in the Tropical 

 Disease Bulletin, and from the reviews of Japanese medical literature 

 by Mills in the China Medical Journal, that material was obtained 

 for the discussion of Japanese papers which were not accessible. Other 

 Japanese writers who have contributed to the knowledge of the struc- 

 ture of the cercaria of S. japonicum are Ogata (1914) and Nara- 

 bayashi (1914, 1916). Notwithstanding the amount of work which has 

 been done on the intermediate stages of S. japonicum there is still 

 considerable confusion and difference of opinion in regard to the 

 structure of the cercaria. 



The discovery of the intermediate hosts and larval stages of the 

 other two species of human blood flukes, S. Jiaematohium and S. man- 

 soni followed closely after that of S. japonicum. Leiper (1915, parts 

 I, II, III) working in the same laboratory from which Looss tried so 

 long in vain to solve the life history of the Egyptian blood fluke 

 found the intermediate host of that species and studied its larval 

 stages. At first Leiper did not distinguish between the cercariae of 

 S. haematobium and S. mansoni. In later publications, however, 

 Leiper (1916, 1918) distinguished between the cercaria of S. haema- 

 tobium which develops in Bullinus contortus and Bullinus dybowsM 

 and the cercaria of S. mansoni which develops in Planorbis boissiji. 

 Leiper did not attempt to make a critical structural analysis or com- 

 parison of the cercariae of these two species. Cawston (1915, 1916, 

 1917) reported the larval stages of ;S'. haematobium in Physopsis 

 africana from South Africa. His descriptions and figures of this and 

 the other forked-tailed cercariae which he described are so entirely 

 inadequate that it seems to me that his entire work needs verification 

 by more competent observers. In the new world the intermediate host 

 of <S'. mansoni has been discovered in Venezuela by Iturbe and Gon- 

 zales (1917) in Planorbis guadelupensis Sowerby and by Lutz (1916 

 and 1917) in Planorbis olivaceus Spix. Initz so far has published only 

 preliminary reports of his work, but promises the full account soon 

 in the Memorias do Instituto Oswaldo Cruz. A second paper by Iturbe 

 (1917) contained a fuller account of the anatomy of this cercaria. It 

 is very probable, as stated by Lutz (1916, p. 387), that Cercaria 

 blanchardi from Planorbis bahiensis was the cercaria of S. mansoni. 

 Da Silva's description of this form is too brief to make certain deter- 

 mination possible, but agrees as far as it goes with the description of 



