TJi c Mouth-parts of the Nemocera, etc. By W. Wesche. 43 



Scatophaga is a haunter of the ivy blossom, and feeds there 

 as well as on fresh cow-dung, besides picking up " unconsidered 

 trifles " in the way of flies. 



The Ortalidse, the Trypetida?, and the Lonclueida?, have no 

 teeth on the paraglossa?, and have numerous minute trachea? some- 

 what like those found in the Pipunculidse. 



Seoptera vibrans L. has curious paired processes on each side of 

 the labium, which may be vestiges of the mandibles ; while the 

 cardines of the maxilla? take a form which is also met with in the 

 Ephydrida? and the Borborida? ; it sends out a limb in the centre, 

 at right angles to the rest of the organ. Ulidia dcmandata F. has 

 the cardines straight, as in the Anthomyida?, as has also the 

 Trypetid Acidia heraclei L. The Lonchseidse have mostly the 

 cardines of the same type as Seoptera (pi. VIII. fig. 1). 



The obscure and difficult family of the Chloropoda? has a dif- 

 ference in the structure of the trachea?, which would enable an 

 observer to separate these insects ; the trachea? are stouter, fewer, 

 and more markedly chitinous (pi. VIII. fig. 2). 



In the parasitic Hipposboscida?, there is a venation well re- 

 moved from that of other families, a modification of shape, and a 

 type of mouth-part, that makes the parentage of this family not 

 at all obvious. But in the mouth-parts are two points that 

 suggest a strong probability of a descent from one of the blood- 

 sucking Muscida?. This is strengthened by a fact in the life- 

 history of Glossina, that insect being viviparous. This would be 

 a step to the curious condition existing in the Pupipara, in which 

 sub-order the young are brought forth as pupa?, having passed the 

 egg and larval state in the oviduct. 



The most striking feature of the mouth-parts is a pair of large 

 palpi, which act as a sheath for a chitinous tube, which is the 

 piercing and blood-sucking apparatus of the insect. This tube 

 has some exceedingly minute serration at its extremity ; and a 

 very high magnification shows these to be teeth, similar, in cha- 

 racter and relationship to their support, to those on the labium 

 of Glossina, Stomoxys and Haimatobia. Further, the tube swells 

 out at its base into a bulb (pi. VIII. figs. 3, 4, 12 ; pi. VII. figs. 3, 4). 



Taking these facts into consideration, I consider the proboscis 

 in Hippobosca as clearly homologous with the same organ in 

 Glossina, Stomoxys, Haimatobia, or Prosena, and it is therefore a 

 modification of the labium, and the palpi are labial palpi. 



It may be suggested that a Tabanid ancestry was not impro- 

 bable, and that a similar serration can be seen on the labrum of 

 the Tabanida?. This objection may be disposed of by showing the 

 labrum as present in some species of the Hippoboscida? as a 

 separate part. The cardines which I have shown to be so constant 

 in Diptera are present, but have changed positions, seeming to 

 work the labium at an angle to the plane of the head. 



