PREFACE 
The series of new blood filariae described in the following pages were found 
during the examination of a large number of West African birds of different species 
for parasites of the red blood corpuscles. The discovery of the blood filariae naturally 
led to a search for their parent forms : but time did not permit of any extensive 
investigations being made as to the nature of their intermediary hosts. 
Opportunities also occurred for observations on human filariasis in West 
Africa, which combined with the work on avian filariasis, will, it is hoped, throw 
considerable light on this very interesting branch of parasitology. 
The description of the parasites has involved a great amount of labour in the 
examination of the literature of the subject, and for this reason, and also because of 
the rapidly increasing importance of the subject, and of the desire for a comprehensive 
work, often expressed by investigators in tropical countries, it has been considered 
desirable to incorporate in this work Stossich's extensive bibliography, and also to 
introduce chapters on the Nematodes in general and the Filariae in particular, for 
the greater part of the matter of which we are indebted to the valuable works of 
Shipley {Worms, etc., The Cambridge Natural History) and Railliet {Zoologie 
medicale et agrkole). 
The authors wish particularly to thank Mr. A. E. Shipley for his useful 
advice and help ; Mr. Robinson, who kindly undertook the identification of the birds 
of our collection ; Dr. A. H. Hanley for much valuable material ; and our colleagues 
at University College for their assistance. 
H. E. A. 
J. E. D. 
J. H. E. 
September, 1901 
