854 



examining the under side of the head of a beetle, 

 the parts of which this lower lip will be found to con- 

 sist are, first, a broad horny plate (ch or c 2) articu- 

 lated at its base, and connected at its extremity by 

 membrane, with a leathery piece (/ 2), within which 

 arises a fleshy organ (t), occasionally having its ante- 

 rior angles elongated (/ ; the labial palpi (/ p) 

 take their rise between the first and second of these 

 pieces. The first named piece is attached to the 

 head by a horny piece (z), which, although appar- 

 ently a'rticulated in some beetles (as for instance in 

 the cock-chaffer, the common Chinese Mimela, &c.), is 

 immoveable, and forms a portion of the throat or 

 jugulum, but which MacLeay regards as part of the 

 lower lip, and calls it stipes. It is the piece prebasi- 

 laire of Strauss- Durckheim. Mr. Newman calls it 

 mentum and insertio, and regards it both as a ter- 

 minal part of the throat, and as a basal part of the 

 lower lip ; at least if we understand him correctly, 

 which it is certainly difficult to do, from the abrupt 

 manner in which his definitions of these organs of the 

 mouth are drawn up. The chin, or mentum (the 

 broad horny piece above-mentioned), is very variable 

 in its form "{ch or c 2), sometimes, as in the lamelli- 

 com beetles, serving exactly as a lower lip, and closing 

 the mouth ; but in other beetles it is shorter and more 

 transverse, and cannot be in the least degree effectual 

 in performing this office. Sometimes even its base is 

 soldered to the jugulum, the stipes being entirely ob- 

 solete, and thus, in fact, becoming the anterior edge 

 of the former. This is the case in Pausstis, Siagona, 

 &c. ; but its true nature may be known by the posi- 

 tion of the labial palpi, which always arise between 

 its extremity and the base of the terminal portion of 

 the lower lip, to which (if with MacLeay, Kirby, 

 Curtis, &c., we continue the analogy with the human 

 face), we must restrict the name of lower lip or labium, 

 although the same name is applied to the whole ap- 

 paratus. This difficulty may be obviated by terming 

 this piece, with Fabricus and others, ligula. The latter 

 piece is more membranous, and of a smaller size than i 

 the mentum, and often serves to close the mouth as j 

 effectually as the former. We therefore see no suffi- 

 cient reason, on this account, for not giving to it the 

 name of the labium, or lower lip. The form of this 

 organ is very variable, and sometimes, as in the tiger- 

 beetles, it is completely concealed by the mentum. 

 On examining the lower lip, internally, a distinct 

 membranous or leathery lining (t) will often be found, 

 the angles of which are protruded beyond the front 

 margin of the lower lip, in the form of little protuber- 

 ances (/ /). These are very conspicuous in many 

 Carabitke, and are termed paraglossae, although thev 

 can only be regarded as the produced angles of the 

 internal organ, which, from analogy, may be termed 

 the lingua, or tongue, and which is very distinct in 

 many orthopterous, and some neuropterous, insects ; 

 in which orders the general structure of the labium 

 (and its various parts) is very similar to that of the 

 beetles, except that in the former, the part to which 

 we have restricted the term labium (or ligula) is divi- 

 ded, longitudinally, into four branches. In the Hy- 

 menontera, however, the labiurn has reached its fullest 

 development ; and this is more especially the case in 

 the bee tribes, to which (without going through the 

 other hymenopterous families) it will be advantageous 

 to direct our attention. We have said that in these 

 tribes the maxillae co-operate with the labium, in order 

 to enable the insect to suck the nectar of flowers. 



INSECT. 



The machinery by which the lower parts of the bee's 

 mouth (to which, from analogy, the term tongue is 



111 



Figs. Ill, Labium of Geotriipes; 112, ditto of Mrlolontfia; 113, 

 ditto of Cicindela; 114, ditto of Gryllus outside; 115, ditto 

 laterally. 



often, but not very correctly, applied) are protruded, 

 is exceedingly beautiful. It has, however, already 

 been described at length in our article, BEE. On re- 

 ferring to vol. I, p. 361, col. 2, the maxillse, and 

 their very minute palpi, will be observed to be ex- 

 tended on each side of the central piece, which, it will 

 be seen, arises from a short triangular piece, which 

 appears analogous to the part which we have noticed 

 above, as the stipes of MacLeay, although here, for 

 evident purposes, it is articulated and moveable. 

 The next piece is the thickened horny tubular piece, 

 or mentum, at the extremity of which arise the labial 

 palpi, remarkable for the elongation of the two basal 

 joints, and between which, at the base, are two short 

 processes, which are termed paraglosste ; the appara- 

 tus terminating in a long and slender many-ringed 

 instrument, which, in the following page, we have 

 called the tongue, or lingua, but its true analogy has 

 not been determined. By some authors it is called 

 the labium. 



In the lepidopterous insects, the structure of the 

 mouth, although having a function similar to that of 

 the bee's, is completely altered as to the form of its 

 individual organs. In the latter, the maxillae and 

 labium conjointly operate in sucking up honey ; but 

 in the former (see fig. 87), the maxillae (mx) alone 

 perform this office, the labium (/2) being rudimental, 

 and attached to the head, and only distinguishable by 

 bearing the pair of large palpi (Ip) which bend up- 

 wards, and form the defence of the spiral maxillae. 

 In the Diptera (see fig. 88), on the contrary, as well 

 as the Hemiptera (see fig. 89), the labium (/ 2) i ( is the 

 most conspicuous part of the mouth, forming the 

 elbowed and fleshy, or articulated and membranous, 

 tube or canal, in which the other organs of the mouth 

 are enclosed. In these orders, moreover, the labial 

 palpi are obsolete ; great variations occur in these 

 orders, and especially in the Dipiera, as regards the 

 form of this lower lip ; but it would lead us to too 

 great a length were we to notice them more in de- 

 tail. The forest flies, Hippoboscidee, and the flea, 

 exhibit other modifications of form of the lower lip. 



Such are some of the more important organs with 

 which Nature has supplied insects, for the due sup- 

 port of their existence. Of their uses we shall speak 

 more at large when we come to treat of the physio- 

 logy of insects, when we shall state our reasons for 

 employing the terms antennae and palpi, which indi- 

 cate no decided use in preference to that of feelers, 

 which is, by many authors, assigned indiscriminately 



