Published online by Cambridge University Press: 31 May 2012
The excellent monographic studies of Brennan (1935) and Stone (1938) on Nearctic Tabanidae and the even more recent catalog of Philip (1947) has placed the study of this group on a firm foundation. The student of this family rarely suffers from a dearth of material since the abundance of individuals of many species, their ease of preservation and their economic importance lead to the collection of long series. As these series accumulate, it sometimes is found that certain species exceed the limits of variation conceded that species, and in other cases what appear to be new forms, may be separated.