The Mouth-parts of the Nemocera. By W. WescM 9 



In the bead, at the back of the submentum of some Psychodidse 

 and also of U. fuliginosa is an appearance suggesting the presence 

 of the pharyngeal pump. If this is so, it would be of the type 

 found in Tipula. 



To this group must be transferred the Lonchopteridse, as fresh 

 dissections have revealed the lacinia? of atrophying maxilla? at 

 the bases of the palpi. These lacinia? are 85 fi or \.} )() -in. long, 

 and I must plead as excuse that it is as easy to overlook as it 

 is difficult to dissect objects of this size (plate T. fig. 17). The 

 paraglossa? are deeply cleft, and, like Leptis scolopacea L., liave 

 plates from which the trachea? spring, on the edges of the clefts. 

 The mandibles are imbedded in the mentum. The trophi of 

 L. flavicemda Mg. and L. scolopacea are "remarkably close to each 

 other both in detail and general plan (plate I. figs. 15, 16, 18). 



The mouth-parts of the Platypezida? also resemble those of 

 Leptis. In Ccdlimyia speeiosa Mg. the maxillae are rather broad, 

 but the cardines and stipites are in an atrophying state ; the para- 

 glossa? are of similar type to that found in Leptis scolopacea L. and 

 LoneJ) opt era flavicemda ; the trachea? are 'more abundant than in 

 Leptis, spring from plates, and the mandibles are imbedded on the 

 ventral side. The paraglossa? -in P. consobrina Ztt. are also of the 

 same type, but the cardines and stipites are quite aborted, while in 

 P. fascia la Mg. they are represented by thin rods, the palpi being 

 very similar to those of L\ consobrina. In other respects as regards 

 the tracheae, the mentum, the hypopharynx, and the labrum, the two 

 last named species are very close to each other (plate II. figs. 27-30). 



All the Bombylida?* I have examined show the mandibles on 

 the ventral side ; alone in this group the Syrphida? have them 

 imbedded on the dorsal side, whence they may easily be dissected 

 out in such large forms as Erystalis or Helophilus. 



Group 3. — I have already alluded to the " pharyngeal pump " 

 in Tipula oleracea L. In this insect it is formed of two plates and 

 is close to the form found in Gidex. I have also found it in the 

 heads of Ptychoptera albimana F., P. contaminata L., P. lacustris 

 Mg., Gynoplistia bella West., and several undetermined species, but 

 it appears to be absent in the Chironomyida? (plate II. figs. 22-24). 



In the Ptychopterida? mentioned above, the trachea? of the 

 paraglossia spring from chitinous plates, in a similar manner to 

 that already noticed in some Leptida? and Lonchopterida?, and the 

 median cleft of the labium is deep. The venation of the Ptycho- 

 pterida? suggests that this family is one of the oldest in Diptera, and 

 the deeply cleft labium is quite consistent with this hypothesis. 

 The plate at the base of the trachea? is more frequently found in 



* Anthrax paniscus Rossi appears to lack the median structure, but appears 

 to have the mentum bent in or furrowed in the median lino ; but 1 have not bid 

 sufficient material to be quite certain. 



