Orthorrhapha l)rachycera. 



is not free, there is no oral cone developed. The proboscis is almost 

 always short, slightly or not at all protruding; only in Orthocliile it 

 is long and somewhat thin, and also in a group of species of Herco- 

 stomus it is somewhat elongated. It is characteristic for the family 

 that the proboscis and the other mouth parts, as well as the oral 

 aperture are often considerably larger in the female than in the 

 male, in accordance with the breadth of the epistoma. The oral 

 aperture is in the whole rather large, stretching more or less up on 



Fig. 1. Dolichojms ungnlatus d". Fig. 2. Tachytrechus ammobates d". 

 Heads showing epistoma and clypeus. 



the occiput. The labrum is strong, and of a curious shape; it is high 

 at the base, broad and arched; it has a less chitinised median tooth, 

 and on each side a strong lateral tooth ; as the labrum is strongly semi- 

 tubular, the lateral teeth lie lower downwards than the median; 

 sometimes the median tooth is not developed. Hypopharynx like- 

 wise strong, it is more or less elongated triangular, sometimes some- 

 what broadly, about of the length of labrum, and like this generally 

 curved a little downwards at the apex; rarely the apex is two-pointed 

 {MedeterusJ. There are no maxillæ, but one-jointed maxillary palpi, 

 which are large, squamiform, more or less oval; sometimes they are 

 very large; they are hairy and generally with one or several bristles. 

 In rest the palpi repose on the front side of the proboscis. Labium 

 short, as mentioned, only longer in Orthochile and some species of Herco- 

 sfomus; it has the basal part about of the length of the labella; these 

 latter are broad, when spread out they form a nearly circular disc 

 surrounding the median cavity; they have generally hairs at the 

 margin. Whon the labella are closed they form together a somewhat 

 wedge-shaped part. Labium rather strongly semitubular, or nearly 

 tubular, its upper edges going somewhat near to each other; the hole 

 thus formed is rallier large. The basal connecting membrane of the 



