ACKNOWLEDGMENTS 



For kind permission to make use of illustrations from already 

 published works the authors are indebted to : — 



The Director of the Carlsberg Laboratory, Copenhagen, for 

 Figure i from Schmidt, J., in G.R. Trav. Lab. Carlsberg, 18, 1930 ; 



Firma Julius Springer, Berlin, for Figure 2 from Zimmermann 

 in Zeitschrift fur Morphologie und Oekol. Tiere ; 



The American Museum of Natural History for Figures 3, 

 10, 11, 12 ; 



Firma Johann Ambrosius Barth, Leipzig, for Figure 4 from 

 a paper by Sikora, H., in Arch, fur Schiffs-und Tropenhygiene ; 



The United States Government Printing Office for Figure 5 

 from Mickel, C. E., in Entomological News, 35, and for Figure 22 

 from Journal of Mammalogy, 7 ; 



The United States Department of Agriculture, Bureau of 

 Biological Survey for Figures 6a, b and c from Howell, A. H., 

 in Bulletin, 37 ; 



The Carnegie Institute, Washington, for Figures 7, 8, 18 

 from Crampton, H. E., Studies on the genus Partula in publica- 

 tions 228 and 410, and for Figure 25 from Lutz, F. E., in publication 

 101; 



Brighton and Hove Natural History and Philosophical 

 Society for Figure 9 from an article by H. Toms in Report, 

 1920 ; 



The Wistar Institute of Anatomy and Biology, Philadelphia, 

 for Figures 19, 19A and 21 from the Journal of Experimental 

 Zoology ; 



The Royal Entomological Society of London for Figure 13, 

 a plate from the Presidential Address, Proceedings, 5, 1931 ; 



The Zoological Society of London for Figure 14 from 

 Ingoldby, C. H., in Proceedings, 1927 ; 



The British Museum (Natural History) for Figure 15 from 

 the ' Handbook of British Mosquitoes ' ; 



Messrs. Ernest Benn, Ltd., for Figure 16 from J. R. Norman's 

 ' A History of Fishes ' ; 



Professor Nuttall and University Press, Cambridge, for 

 Figure 26 from Parasitology, 4, 191 1 ; and 



University Press, Cambridge, for Figure 30 from Himmer 

 in ' Biological Reviews,' 7, 1932. 



Beneath each illustration is the reference to a source which is 

 set out in full in the Bibliography at the end of the volume. The 

 Table on page 97 is translated from Rensch, R. B., in Arch. Naturges. 

 1, by permission. 



