Diptera: Nemocera vera, N. anomala and Eremochaeta. 421 



multiarticulate antennae {Xylo-phagus, Suhula, Caenomyia etc.) and 

 to reach the conclusion that the pretended line of division between 

 the iwo groiips had no existence in reality. 



In the chapter „On the terminology of Diptera" (Monographs 

 N. Am. Dipt. Vol. I, p. 2—4, 1862) Loew discusses the limits of the 

 Nemocera and Bracliycera and concludes by saying: „It is a fact, 

 that some discoveries made in modern times have obliterated to a 

 certain degree the sharpness of the limit which was considered to 



exist between the cwo sections etc All these facts however 



are not sufficient to oblige us at present to give up the Separation 

 of Nemocera and Brachycera" etc. In other words, Loew seems 

 to have feit that the subdivision is well founded in nature, although 

 he was not able to dehne it; he did not know that, long before bis 

 time, a very good distinctive character had been found in the palpi. 

 The same train of reasoning is maintained by Loew in his lecture 

 „lieber die Dipteren-Fauna des Bernsteins", written in the same year 

 1860, which is the date of Loew's Preface in the Monographs etc. 

 Vol. I; it does not contain a Single allusion to the palpi (read, 1. c. 

 p. 7, column first, the passage which begins with: „Schon seit längerer 

 Zeit" etc. and ends in the next column.) Loew's conclusion in this 

 jnstance is that the transitional forms between the two divisions 

 exist npw, just as they existed in the tertiary period, and that if 

 they were noticed for the first time in the amber-fauna, is was be- 

 cause they are extinct in Europe, and were discovered only later in 

 other continents.i) In this Loew was completely mistaken; transi- 

 tional forms have not been discovered yet, neither in the living, nor 

 in the fossil faunas. We do not know a Single dipteron yet, whose 

 Position between the two divisions is doubtful. 



The climax was reached in 1863, when Snellen vanVollenhoven 

 discovered in the Museum in Leyden a fly that he called „Anti- 

 doxion" , which means: „against the doctrine", and which afterwards 

 was proved to be the same as Rhachicerus. In his article on this 

 subject (Verslag en Mededeeling d. K. K. Ak. v. Wetensch. Vol. XV) 

 van Vollenhoven discusses the two divisions proposed by Latreille, 

 and accepted by later authors; he reproaches them with their incon- 

 tistency, in not at once rejecting these divisions, and especially takes 

 to task Loew, „den grootsten Dipteroloog van onze dagen" for the 

 hesitation expressed by him in the passage already quoted „All these 

 facts liowever etc." (see ante). VanVollenhoven, in producing his 



i) An earlier passage, in the same sense, will be found in Loew, 

 Berl. Ent. Z. 1858, p. 102. 



