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University of California PuMications in Zoology [Vol. 18 



The central nervous system is an oval, slightly irregular mass lying 

 about the center of the body (figs. 2, 3, 4, n) . My observations on 

 the living animal did not reveal the nerve fibers going out from this 

 central mass as shown by Looss (1896, p. 165, pi. 11, fig. 113). Hol- 

 comb (1907, p. 68) entirely misses the significance of this structure. 



Fig. 3. Miracidium of S. mansoni within the egg, from neural surface; 

 letters as in figure. 2. 



and calls it a viscus or stomach connected with the anterior end by an 

 esophagus. He was also confused in regard to the structures of the 

 posterior part of the body. His errors are surprising, since an 

 acquaintance with the general structure of the miracidium stage of 

 the trematodes or with the description or figures of the miracidium 

 of Schistosoma haematobium would have made them impossible. It is 

 unfortunate that his figures have found their way into some of the 



