

The few diptera whose mouth-parts have been the object of the anatom- 

 ical studies, the results of which are noted in the following pages, were 

 chosen, on the one hand, with especial reference to their presenting a series 

 beginning with a species possessing simple, separate and fully developed mouth- 

 parts, and ending with a species of which the complexity of the mouth-parts 

 was due to coalescence and incomplete development of their different elements, 

 and, on the other hand, with partial reference to forms whose mouth-parts were 

 of sufficient length to render their study by sections, made with the microtome, 

 of value in determining their relative lengths, their positions and their attach- 

 ments. With the above-mentioned objects in view species of the genera Cuk.i; 

 Bombylius, Installs, and Muxca were chosen. Upon the anatomy of the mouth- 

 parts of Culcx the following notes probably add most to what has been previously 

 recorded. No study of the development of the mouth-parts has been made in 

 preparing the following paper; the results are anatomical only. 



The work necessary for the preparation of this paper was done by me, 

 as student, in the Laboratory of the Zoological Institute in Leipzig, and I gladly 

 take this opportunity of expressing my sincerest thanks to its director, my 

 honored instructor, Professor Leuckart, for the advice and encouragement which 

 he has given me in my studies. 



HISTORICAL. 



Until FABRICIUS, in J7<5, first called attention to the importance of the 

 mouth-parts in the classification of insects, little or no valuable progress had been 

 made in the study of their comparative anatomy. Observations on the anatomy 

 of the mouth-parts of single insects are to be found in the works of many 

 writers, previous to the above-mentioned date, but they can be best regarded as 

 forming only a part of the history of the anatomy of single insects, and, so far 

 as they treat of insects which are further discussed in this paper, they will be 

 mentioned later. 



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