EXTERNAL ANATOMY OF INSECTS. 21 



to the two usually described. The apex of the ligida, and the 

 form of the articulations of the feeler, seem to be the only por- 

 tions of the lip in this class that are likely to be available for 

 generic distinctions. 



In Diptera, the lower lip is the largest and most conspi- 

 cuous portion of the mouth. It is the organ known to every 

 one, with which the busy house-fly attacks our sweets. It is 

 not unfrequently termed the proboscis of the fly, a term, 

 however, applied by Meigen to the united mouth of Citlex."' 

 Desvoidy, as already stated, has another idea about the ana- 

 tomy of this organ. Tiie ligida of Hymenoplera, shortly to 

 be noticed, appears to have a precise analogue in the incrassated 

 bilobed termination of the lip oi Diptera. Immediately below 

 this, in the genus Tabumis and some neighbouring groups, 

 may be seen on each side of the lip a pilose excrescence. 

 Savigny considers this the labial-feeler. It is the very situation 

 in which analogy will lead us to look for this organ ; and the 

 idea that it is such is, consequently, far from improbable. I have, 

 with great pains, sought for some character, whereby I might 

 with confidence confirm Savigny 's opinion, but have been un- 

 successful : there appears no trace of articulation. By a careful 

 examination, and frequently turning the object in the light 

 while the eye is fixed on it, a nearly direct line will be seen 

 crossing the lip immediately below these excrescences, thus 

 separating, as I conjecture, the feeler - bearer from the true 

 labium. The insertion is distinct ; it has been noticed and 

 figured by Savigny and others. The divisions of the lip are 

 more prominent in Empis, Stomyxis, Rhingia. &c. than in 

 Tabaniis ; yet still sufficiently indistinct, and scarcely to be 

 recorded with certainty. The conspicuous presence of four 

 divisions in the lip of Ilymenoptera, Coleoptera, Orthoptera, 

 and Hemiptera, led me to expect them in Lepidoptera and 

 Diptera. Let me not influence the judgment of others. I 

 have satisfied myself by patient investigation : I hope my 

 fellow-labourers will do the same. With the exception of the 

 ligida, the lip of Diptera affords but few characters for generic 

 descriptions. 



We now arrive at the Ilymenoptera. Here the lower lip 

 reaches its maximum. Let us examine the mouth oi Bombus, 

 the humble-bee. This mouth, if neatly spread out, presents 



" Culcx. Proboscis porrectu, loiigitudinc thoracis. — lUcigen. 



