ILLUSTRATIONS 



methods of feeding 51 



XIII-XIV The Receptaculum Seminis of Female British 



Bird Fleas and Mammal Fleas 66-67 



XV-XVI Terminal Portion of Male British Bird Fleas 82-83 



XVII Common House-Martin Flea 98 



XVIII Life-Cycle of Flea 99 



XIX Pygidium of Flea 114 



XX Swan 115 



vu 



