iv PREFACE. 



Indies and Mexico. But if, instead of the sixty pages which the 

 above-mentioned essay contains, the present volume fills nearly 

 three hundred and sixty, this is owing partly to the increase of 

 materials at my disposal, partly to the much greater development 

 which I have given to the paragraphs concerning the classifica- 

 tion. When, in 1859, I adopted an entirely new distribution of 

 the Tipulidse, I considered it as only provisional, because it was 

 based exclusively on North American species. Since then, how- 

 ever, it has proved available in a more general application, 

 and has been introduced by Dr. Schiner in the European fauna. 

 I have therefore deemed it necessary to explain my views on that 

 distribution with more accuracy, and have treated the classifica- 

 tion with almost as much detail as if I was writing, not a faunistic, 

 but a general monograph of the family. I only regret that my 

 opportunities for studying the European fauna have been so 

 limited. As to the Tipulidse from the other parts of the world, 

 besides Europe and North America, they are hardly known at all. 

 The little I have seen of them in the principal museums of London, 

 Paris, Berlin, and Turin, has been made use of by me. 



My principal collecting grounds have been the environs of 

 Washington, D. C, and of New York. I have made occasiolaal 

 excursions to different parts of the States of New York and 

 Pennsylvania and in New England ; moreover, I have received 

 contributions from my friends in New England, and not unim- 

 portant collections from the northwestern region of this continent, 

 sent by the lamented Robert Kennicott. Thus, as far at least as 

 the more common species are concerned, the Middle and Northern 

 States may be said to be tolerably well represented in this volume ; 

 less so, the region west of the Alleghanies and the British Pos- 

 sessions. The country south of Washington is almost unexplored. 



I owe a debt of deep gratitude to my friend Mr. Samuel Powel, 

 in Newport,. R. I., who devoted a great deal of valuable time to 

 the preparation of magnified photographs of the wings, intended 

 to be represented on the plates I and II to this volume. These 

 photographs were transferred to steel by the process of Baron 

 Egloffstein. The plates thus obtained present a degree of fidelity 

 to nature hardly attainable by the ordinary processes. The plates 

 III and IV, drawn by my own unskilful hand, are reproduced 

 from my earlier essay ; only the arrangement of the figures on 

 them has been changed. 



