6 THE EARLY STAGES OF TABANID^ 



In grouping the material I have as far as possible followed a system- 

 atic arrangement, by bringing all the facts which could be referred 

 with certainty to a definite species under the heading of that species, 

 even where the facts appear to apply to a whole genus or to tabanids 

 in general. In each species the egg stage is first treated, followed by 

 the larval and pupal stages. Results obtained by one author in one 

 paper have, consequently, often been separated and rearranged. On 

 the other hand, no attempt has been made towards extensive gen- 

 eralization; the general statements on the family Tabanidae and the 

 more important genera are only such as are found already in the 

 literature, and are not to be considered as final or as expressions of the 

 author's opinion. 



In the arrangement of the plates a slightly different plan has been 

 followed, as it seemed desirable to facilitate the comparison of corre- 

 sponding stages. I have therefore figured on Plates 1 and 2 all the 

 existing illustrations of the egg stage of different species; on the fol- 

 lowing plates the larvae and larval structures; following these the 

 pupge; and finally pupal structures, these being of especial sys- 

 tematic value. With this arrangement the different stages of the 

 same species are necessarily separated and figured on different plates. 

 In the details, the arrangement has been such as seemed most con- 

 venient. Occasionally an exception to the general order has been made 

 and a group of figures illustrating one species or genus appears 

 on the same plate. 



