34 Transactions of the Society. 



forming a triangle ; these remind me of Savigny's often quoted 

 vestiges of labial palpi on Tabanus italicus, though they are 

 differently placed. I regard them as the palpigers, as their situa- 

 tion corresponds with the position of the labial palpi in Dilophus 

 (pi. IV. fig. 5 ; pi. VI. fig. 6). They then explain the constant 

 appearance in the Muscidae, calyptrate and acalyptrate, of rows of 

 hairs at the base of the labial palpi, though the position is much 

 more posterior. I also find on the labium of T. siideticus Zlr., a 

 cluster of fine hairs in the same place as the palpigers are on in 

 Chrysops (pi. VII. figs. 6, 8; pi. VIII. figs. 6, 11 ; pi. III. fig. 3). 



In Pangonia is found an extraordinary development in the 

 leugth of the labium without the geniculation that usually accom- 

 panies this character. This enables these insects to pierce through 

 clothing to the skin. The figure gives the mouth-parts of the 

 male, and it will be noted that like the normal male Culex, it is 

 without mandibles. The female has a full armature, and certainly 

 belongs to Group 1 (pi. IV. fig. 1). 



The Asilidae, which prey on other insects, have the labium 

 hardened and horny, the hypopharynx ciliated, (showing, as will 

 be seen later, its relationship to the Nemocera,) and the maxillae 

 very broad and strong; the maxillary palpi have but one joint 

 (pi. IV. fig. 12). 



Group 2. — The large family of the Empidae are raptorial, con- 

 sequently the maxilhe are well developed ; they carry a single- 

 jointed palpus, which is often annulated at the base. In this 

 family the paraglossae have but few tracheae, but both the labrum 

 and hypopharynx are almost invariably large and strong (pi. III. 

 fig. 6). 



In Hybos femoratus Mull. I find a remarkable difference in the 

 palpi, which are labial, and placed as in the Muscidae. The 

 maxillae seem atrophying, and are slightly ciliated at the tip ; the 

 hypopharynx is very strong and channelled with a large tube 

 leading down to the pharynx ; this seems the offensive weapon, 

 as in Scotophaga. In Ocydromia glabricula Fin. the palpi are 

 also labial, and the whole labium somewhat of the Musca type 

 (pi. IV. fig. 18). 



In Lcptis scolopacea L. the maxillae are broad and strong, but 

 the labrum, and particularly the fine, acute hypopharynx, seem 

 better adapted for skin-piercing purposes ; the labium is large, and 

 though the tracheae are relatively small, they are fairly numerous. 

 This insect has been reported to attack man, but nothing exact has 

 been recorded. In June 1903 Mr. F. V. Theobald gave me a female, 

 which had bitten him at Wye, in Kent, and from that insect the 

 figure in the plate is drawn (pi. IV. fig. 19). 



In the suctorial group, the My cetophilidae have minute maxillae 

 at the base of the three-jointed palpi; the hypopharynx is ciliated 



