WERNER MARCHAND 11 



on a tabanid larva issued from an agricultural institution. Riley 

 apparently was interested in all insects and their development, and 

 in fact included in his Reports also some insects of no economic 

 importance. 



A great step in advance was made when in 1895, Hart, in Illinois, 

 probably interested by Walsh, who had lived there, but probably also 

 not without some knowledge of the studies of the Vienna school, under- 

 took to investigate the entomology of the Illinois River on a large 

 scale. He described large numbers of new dipterous larvae, and inci- 

 dentally a number of tabanid larvae, notably those of Chrysops 

 vittatus, Tahanus stygius, nigrescens, lineola, and costalis, which were 

 not known before, and giving a preliminary classification by which 

 these larv£e could be separated. Hymenopterous egg parasites of 

 Tabamis, previously seen by Kollar, were then for the first time ex- 

 actly described by Ashmead, who cooperated with Hart. I do not 

 think that Hart could have achieved his results without a knowledge 

 of Brauer's monograph, which had, in fact, appeared ten years before, 

 and which, as stated, contains references to most of the previous 

 w^ork. But as he, apparently following Agassiz's principle, "Study 

 nature, not books," makes no mention of the previous literature on 

 this subject, I assume this to be the reason why later authors, Hine, 

 and even Lecaillon, have lost the thread of tradition pertaining to 

 their subject, and why important results such as the descriptions 

 of numerous larvae and the discovery of Graber's organ have been 

 overlooked by American and European authors. Shortly afterwards, 

 in 1899, the insect volume of the Cambridge Natural History, by 

 Sharp, appeared in England, which also does not mention the litera- 

 ture, but contains the description of an unknown tabanid larva, 

 referred to by Sharp as Tahanus {? Atylotus fulvus) . 



In America new discoveries of tabanid early stages were made by 

 Hine, who, continuing Osten Sacken's work in this field, has become 

 the leading authority on the Tabanidae of North America, especially 

 from the systematic point of view. In 1903 he described the Hfe 

 history of Tahanus vivax; this paper was followed by a publication on 

 the Tabanidae of Ohio, which also contains notes on the early stages. 

 It is worthy of note that Hart's as well as Hine's first publications were 

 not issued by economic but by scientific institutions (Illinois Biolog- 



