DASYPOGONIN.g^. 705 



anal cell ranging from being closed at a fair distance from the wingmargin to being 

 well open, tliough of course considerably contracted towards the wingmargin. Alula 

 and liind angle of the wing usually well develo])ed, and distinctly so in those cases 

 in which the claws are abnormally long and the pulvilli absent. Squamte (alar) fairly 

 large, sometimes provided with a long tuft in the fringe near the fold which seems to 

 act as a substitute for the metapleural fan {Sfenojwgon, etc.) ; thoracal pair absent. 



The character of " marginal cell open " was for a very long period the 

 only one used for distinguishing the Dasypogonince from the rest of the 

 Asilidce. In recent times however two or three different attempts have 

 been made to distinguish the Leptogastrince (which will be dealt with 

 further on), and it has been urged that it may be better to include in the 

 Lasypogoninai a few species (which had previously been included in the 

 Laphrince) in which the marginal cell is, closed at the wingmargin through 

 the more or less abrupt up-turning of the radial vein at its end, and the 

 blunt ending of the marginal cell caused thereby; perhaps the most 

 distinctive character of the Dasypogonince lies in the comparative shortness 

 of the subcostal vein, so tliat in this subfamily it is only through an effort 

 (so to say) that the radial vein occasionally succeeds in uniting itself to the 

 subcostal vein, while in the Asilince and Laphrincv the subcostal vein is 

 so long that the radial cannot help ending in it. I would also call 

 attention to the usual absence of any pubescence (or at any rate bristles) 

 from the hypopleurse as compared with the continuance there of the meta- 

 pleural fan in the Asilince, while possibly some unexamined characters 

 remain to be investigated in the development of the prothoracic collar. 



The boundary line between the Dasypogonince and Leptogastrince is not 

 yet definitely settled. I have laid stress on the character of the claws 

 and pulvilli because it cannot cause any doubt in our British species, but 

 it may not be satisfactory in all cases, as in Stcnobasis the pulvilli are 

 obsolete on the posterior tarsi but almost normally developed on the front 

 tarsi; the characters of the elongated body, very long hind legs, and 

 rather clubbed hind femora seem to be insufficient as a distinction, while 

 I am unable to follow Williston's character of one-jointed palpi in 

 Lcptogastrince as a distinction from the Dasypogonince with two-jointed 

 palpi ; any character derived from the development or degradation of the 

 alula and hind angle of the wing seems to be undecisive but yet may be 

 worth further investigation. Perhaps the extremely limited ch?etotaxy 

 of the Lcptogastrince may afford a distinction, but then Dioctria and allied 

 genera come very close. 



The Dasypogonince are usually elongate rather bare species, and (in at 

 any rate the forms near Dioctria) are weaker and more sluggish than 

 the Asilince. They include some very large flics, though only rarely 

 reaching the size of the largest Asilince or Lophrinm, and on the other 

 hand they include the smallest species of the whole family. The chief 

 prey of Dioctria is Lhncvmoniclce, though they capture insects of various 

 other orders, and the predatory habits of the family have been dealt 

 with in considerable detail by Prof. Poulton in his article on " Predaceous 



2 Y 



