425 



STUDIES IN LIFE-HISTORIES OF AUSTRALIAN DIPTERA 

 BRACHYCERA. 



Pabt I. Stkatiomyiidae. 



No. 3. On the structure of tlie mouth-parts and pharynx of the larval 



Metopunia nibicepK. 



By Vera Irwin-Smith, B.Sc, F.L.S., Linnean Mackay Fellow of the 



Society in Zoology. 



(Plate xxxiii., and twenty-six Text-figures.) 



No satisfactory description exists of the mouth-pai'ts of any larval Slratio- 

 mi/iidae other than a few aquatic species. Vaney (1902) and Jusbaschjanz 

 (1910) have done some work on the genera Stratiomi/ia and Odontomyia; an<l 

 Becker has taken the genus Stratiomi/ia as the type of the family Stratiomyiidae 

 in his general account of the mouth-parts of Dipterous larvae (1910). But 

 many of the features present in this genus, such as the great development of 

 tufts of hairs on the jaws, must be regarded as highly specialised adaptations 

 to the aquatic mode of life, and a more typical form must be looked for in the 

 soil-inhabiting species. Very few attempts have been made to study these in 

 detail. Tragardh's description of PacJujgaster miitutissima (1914) contains a 

 bi'ief account of the head and mouth-parts, with several Hgures, which, un- 

 fortunately, are not very clear. He points out the difficulty of getting a good 

 idea of these structures, and of their homology with those of other fly larvae. 

 Indeed, most Dipterologists, from Brauer onwards, who have studied tlie larval 

 forms, mention the great technical obstacles in the way of their elucidation. 

 The parts are all very minute, and are composed of such dense chitin that the 

 clearing, sectioning, or dissection of them seldom gives good results. The 

 knowledge of the mouth-parts of the whole group of Diptera Brachycera is, 

 for this reason, very meagi-e. Brauer, forty years ago, made an excellent com- 

 ])arative study (1883) of the material then at his disposal, and Becker has 

 since contributed (1910) some additional information on the same subject, from 

 the study of a few more representatives of the different groups. But he, too, 

 draws attention to the paucity of the data on which to make generalisations and 

 to interpret the nature of the separate mouth appendages. Therefore, until 

 the larvae of all the families of Brachycera have been studied in greater num- 

 bers of species, and in greater detail, I do not think it possible to add any- 

 thing of value in this connection ; and, for this reason, I have not attempted, 

 in the following description, to compare the various structures with those 

 described in other Stratiomyid larvae, and in the larvae of any other of the 

 Brachycera. 



