iv First Report on Economic Zoology. 
far more extensive work in the pure science of Natural History, 
which is the primary occupation of its official staff. The Trustees 
published in 1901 a descriptive treatise on Mosquitoes in three 
volumes, with forty-two plates, which was prepared by Mr. Theobald 
in connection with the specimens of Culicidse already in the Museum, 
and others specially collected for the work, with a view to assisting 
in the study of the relationship of Culicidse to Malaria and other 
diseases. A supplementary volume of this work, by Mr. Theobald, 
has been completed and published in the present year. Also in the 
present year the Trustees have published an illustrated monograph 
on the Tsetse-flies, by Mr. Austen, Assistant in the Zoological 
Department. Our rapidly increasing knowledge of the activity of 
the minute parasites known as Trypanosoma, as the specific causes 
of disease both in man and in horses and cattle, renders an accurate 
knowledge of the species of Tsetse-flies necessary, since one of these 
flies, the Glossincc moritans of Westwood, is the carrier of the 
Trypanosoma causing the deadly disease of horses and cattle known 
in South Africa as Nagana, and it is possible that other species of 
Glossina are concerned, in a similar way, in the distribution of 
disease. 
It is not, however, only in correspondence and publications, and 
in the researches of the naturalists of the staff that this Museum 
renders direct assistance to the development of the knowledge and 
application of Economic Zoology. The large study collections of the 
Museum have, for a long time past, comprised important series from 
all parts of the world of carefully named and recorded specimens of 
animals having economic importance, either as pests or as sources of 
commercial products. In addition to these, several cases are now 
exhibited in the North Hall of the Museum, in which the life-history 
and activities of animals important to man in one or other of the 
relations recognised in the classification adopted in this volume, are 
illustrated with a view to the edification of the public, and the 
promotion of the public interest in the thorough scientific treatment 
of the subject. 
I have to thank the Board of Agriculture for permission to 
reproduce some of the Reports furnished to the Board. 
E. RAY LANKESTER, 
Bkitish Museum (Natural History), 
London, S.W. 
May 15th, 1903. 
