PREFACE. 3 



I am much indebted to my highly respected friend Baron C. R. 

 Osten Sacken, who has been so kind as to review the manuscript 

 of my work , especially with respect to the Nemocera and the first 

 families of Brachycera (Stratiomyidae, Tabanidae , etc.). As he has 

 examined numerous types in the first rate public museums and 

 private collections in Europe, he was able to point out to me some 

 omissions or confusions about nomenclature and synonymy, which 

 has led to many completions and corrections. 



The present Catalogue has by no means any claim to be an 

 example of the systematical arrangement of Dipterous insects. In 

 the succeeding series of the families and groups I have only fol- 

 lowed the method, which at present most generally is adopted. 

 The series , in which the genera are placed , are still less to be 

 considered as representing any natural relationship to another, 

 which in many cases is difficult , if not impossible to state. 



In the genera, which contain more than one species, these 

 latter are enumerated in a series according to the date of their 

 publication. 



Indications of synonyms , so far as they are known to me , have 

 been noted; and where a generic name was preoccupied or a specific 

 name was already used in the same genus , I have mentioned this 

 fact, leaving to a future author or monographer, to replace the 

 most recent name by a new one. 



The geographical extension , observed in the Catalogue , includes 

 the southern part of China , the two large penmsules of India 

 with Ceylon and other neighbouring islands, the Malayan archipelago, 

 the Philippine islands and New Guinea. Species of the north 

 of China and of Japan are thus omitted. 



