8 ILLINOIS BIOLOGICAL MONOGRAPHS [296 



with his earlier collecting at the above-mentioned Canadian Biological Stations; 

 to the University of Illinois for the opportunity of collecting further material 

 at the Marine Biological Laboratory at Woods Hole, Massachusetts, and at 

 the Harpswell Laboratory, South Harpswell, Maine, during the summer of 

 1916, and to the staffs of these institutions as well as to that of the Marine 

 Laboratory of the United States Bureau of Fisheries at Woods Hole for assis- 

 tance and direction in connection with the same; to the Smithsonian Institute 

 and the Bureau of Animal Industry, from whom valuable material was obtained 

 for comparison, in the latter case thru the kind offices of Dr. C. W. Stiles of 

 the Hygienic Laboratory, Washington; and to the following investigators 

 for alcohoUc specimens: Professor O. Fuhrmann, University of Neuchatel, 

 Switzerland, Professor Edwin Linton, Washington and Jeflferson College, Pro- 

 fessor E. M. Walker, University of Toronto, Dr. H. J. VanCleave, University 

 of lUinois, Dr. G. R. LaRue, University of Michigan, Dr. A. S. Pearse, Univer- 

 sity of Wisconsin, and Messrs. H. R. Hill and R. P. Wodehouse. 



Finally to Professor H. B. Ward the writer wishes to express his sincere 

 indebtedness not only for the use of his extensive private library and collections 

 and for the procuring of rare books and specimens, but for his constant and 

 stimulative interest in, and valuable criticism of, the work which has resulted 

 in the following paper. 



HISTORICAL DATA 



Apart from Gmelin's (1790) collecting together the data given by the older 

 writers such as Linnaeus, Pallas, Miiller, Goeze, Bloch, Fabricius, Batsch, 

 Schrank and Abildgaard, and Zeder's (1800, 1803) treatises, the first most 

 important work on the bothriocephalid cestodes was the Entozoorum Historia 

 Naturalis by Rudolphi (1808-1810). In this he reviewed the earUer literature, 

 making valuable comments on the same, and described species of Ligula, 

 Triaenophorus and Bothriocephalus, the latter name being used for the first 

 time. While Lamarck (1816) dealt with only the more common species, 

 Rudolphi in his second work of major importance, the Entozoorum Synopsis 

 (1819), made some corrections of his earlier publication and further contribu- 

 tions in the way of a few new species. F. S. Leuckart (1819), who did not receive 

 Rudolphi's Entozoorum until after his own work was in print, dealt only with 

 species of the genus Bothriocephalus as conceived by Rudolphi, which then con- 

 tained members not only of the Pseudophyllidea but also of the TetraphyUidea 

 and the Trypanorhyncha. Nitzsch (1824) briefly defined the species of the 

 same genus, while later Creplin (1839) dealt with them more in detail and 

 erected the new genus Schistocephalus. Drummond (1838) was one of the 

 first to report bothriocephalids from the British Isles, while BeUingham (1844) 

 and Thompson (1844) made further contributions, all three deahng with forms 

 from Ireland. Eschricht (1841) pubhshed some of the earliest data on the 

 internal anatomy of the group, and KoUiker (1843) made a study of the 

 development of the eggs of a few species. The next and perhaps most impor- 

 tant work was that by Dujardin (1845) who, while following Rudolphi in the 



