INTRODUCTION. 
Tiie collections officially obtained and sent to the Natural 
History Museum from all parts of the world since the beginning 
of the year 1899 furnish the chief material upon which the 
present work is based. The collection previously existing in the 
Museum, though not extensive, has proved to be of considerable 
importance. I have received great help in the way of collections 
and information from South America through the kindness of 
Dr. Lutz and Senhor Moreira. To Professor Howard I am 
similarly indebted in regard to collections from North America. 
Besides these a large number of collections and isolated 
specimens have been received by me unofficially, many of the 
collectors having given me permission to make vdiat use I like 
of the unique specimens. These will be deposited in the general 
collection at the Museum. 
As many of the old descriptions of Culicidae are very vague, 
and were compiled when but few species were known, the work 
of identification has been extremely difficult, and probably in 
several cases, could the types be traced and examined, my 
identifications would prove erroneous. Several of the old 
descriptions will apply to more than one distinct species, whilst, 
on the other hand, some totally different descriptions' have been 
shown, by means of an examination of the types, to be actually 
taken from the same insect (vide M. alternans , p. 269, and 
S. fasciata, p. 289). Many of the older descriptions have 
evidently been drawn up from worn and imperfect specimens ; 
and as the characters, coloration, &c., of the family Calicidae lie 
mainly in the scale ornamentation, such diagnoses are practically 
valueless. 
The whole classification in this monograph is mainly based 
on the scale structure. 
The short description of each species given first has been 
drawn up under a hand-lens. The majority of the specimens have 
been received in excellent condition. A few have been attacked 
by mould, some by mites, and a few damaged beyoml repair 
