349 



INSECTA. 



INSECTA. 



250 



the term labium to express the whole apparatus, and describe the 

 several parts under the three heada Palpiger, Mentum, and Stipes. 



Fig. 13, Labium and maxillae of the Hornet. Fig. 14, Labium of Ceramlyx 

 tnotchutiu. Fig. 15, Maxilla of the same insect. Fig. 16, Labium and maxilla; 

 of a Locust. .Ft?. 17, Labium of another species of Locust. In all these figures 

 the letters refer 6 to the palpiger ; c, lingua ; d, paraglossa) ; , palpi-labiales ; 

 /, mentum ; j, cardo of maxilla ; k, stipes of ditto ; /, palpifer ; m, lacinia ; 

 n, galea ; o, palpi-maxillarei. 



Palpiger, or palpi-bearer. This name was first applied by Mr. 

 Newman (' Entomological Magazine,' vol. it) to a portion of the part 

 called lingua by Kirby, and labium by M'Leay and others. It will 

 be used in this article as the name of the whole apparatus to which 

 the labial-palpi are attached, including the lingua, paraglossse, and 

 palpi-labiales. 



The several parts of the labium therefore will be thus divided : 



f Lingua (c). 

 r-Palpiger (6). 



LabiumJ Mentum (/) 

 (.Stipes (y). 



If we examine the underside of the head of any insect in which the 

 various parts of the mouth are well developed, the palpiger will be 

 readily distinguished from the other two portions of the labium by 

 its bearing a pair of palpi, the palpi-labiales. In Dyt.i*cu marginalia, 

 a common water-beetle, the palpiger is of a square form, or nearly so. 

 The broad piece furnished with bristly hairs along its anterior extre- 

 mity in the lingua. On each side of this piece there is a small plate 

 (apparently divided), which has its posterior margin recurved, so as 

 to lie close to the underside of the lingua, and furnished with a fringe 

 of hairs. These small pieces we conceive to be the analogue of the 

 parts called by Kirby paraglossa:, and which are distinct in the bees, 

 wasps, ftc. They also appear to represent the two leaf-like appen- 

 dages at the apex of the palpiger in Cerambyx, the lingua here being 

 nearly obliterated, and consisting only of an extremely minute 

 divided process furnished with hairs. 



The palpiger is not very distinct in the Hymenoptera; its appendages 

 however are often greatly developed. In the hornet the lingua is 

 very large, broad, and divided at the extremity ; the paraglosso; are 

 also large. The labial palpi are long, and composed of four joints. 

 The lingua in many bees is of great length, and the paraglossa' are 

 often long. The labial-palpi in the typical bees are flattened, and 

 have the basal joint long. 



Orthopterous Insects have a well-developed palpiger : the lingua, 

 paraglossse, and palpi are distinct. 



Mentum, or chin, by which we mean the part so called by M'Leay, 

 Westwood, and indeed most modern authors, but which is the labium 

 of Kirby and Newman. The mentum is the piece below the palpiger, 

 and generally articulated to the stipes by a membranous hinge. This 

 part is very variable in shape, and is consequently often referred to in 

 descriptions of insects, or rather in definitions of the genera. It is 

 generally distinct in mandibulate insects. 



In Dytiscus marginalia it is of a transverse form, and emarginated 

 on the fore part. In the hornet, as well as in the bees, the mentum 

 is long, and nearly cylindrical. 



Stipes. This name is applied by M'Leay to that piece which is 

 below the mentum. It is the meatum of Kirby, the ' pidce prebasi- 

 laire' of Straus-Durckheim, and the insertio of Mr. Newman. 



The stipes is generally soldered to the jugulum, so that its bounda- 

 ries cannot be detected. Such is the case in the water-beetle, the 

 head of which is selected to illustrate this article. Its lower 

 boundary is indicated in the figure by a dotted line. In the common 

 Cockchafer (Melolontha vvlgaris) however it forms a well-defined 

 piece. In AmpkimaUa solttitiali* (fig. 7), an allied insect, it is also 

 distinct. In the Hymenoptera the stipes is small, and generally of a 

 triangular shape. 



The Mandibles (Mandibulae) come next under consideration. These, 

 the representatives of jaws, are situated immediately below the labrum. 

 They are two in number, and have a vertical motion. 



In the Mandibidata the mandibles are almost invariably of a hard 

 horny nature, often of a triangular form, or nearly so, and furnished 

 with pointed processes (which have been compared to teeth) on their 

 inner side. 



In Carnivorous Insects the mandibles are usually of moderate length, 

 sharply pointed, and armed internally with acute processes. Wood- 

 boring insects, such as the Cerambycidtz, have short stout mandibles ; 

 and in those insects which feed upon vegetable substances (the 

 Phyllophagi, &c.) the mandibles often present a broad grinding 

 surface on their inner side near the base. 



Fig. 18 



Fig. 



Fig. 20. 



Flijs. 13, 19, and 20, Maxilla; of various insects. 



The Maxilla;, or feeler-jaws, like the mandibles, under which they 

 are placed, are opposed to each other horizontally. They are joined 

 at their base to the labium, and distinguished by their giving attach- 

 ment to the maxillary palpi, on which account Mr. Newman has 

 applied to them the name of feeler-jaws. The maxilla; are variable 

 in form, and hence the characters of genera and larger groups are rat 

 unfrequently derived from them. A perfect maxilla presents five 

 distinct portions the Cardo, Stipes, Palpifer, Lacinia, Galea, and 

 Palpi-Maxillares. 



Cardo (the hinge) is a small piece, often of a triangular form, upon 

 which the maxilla sits. It is the Insertio of Newman.* 



Stipes (the stalk). Kirby applies this name to the " corneous base 

 of the maxilla, below the palpus," and in his detailed account of this 

 part refers both to the palpifer and another portion which is generally 

 situated within the palpifer. We shall confine the name stipes to 

 that part of the maxilla which is joined to the cardo, and is either 

 within or below the palpifer. It is the Maxilla, or Disc, of Mr. 

 Newman.t 



Palpifer. This part, to the summit of which the maxillary palpi 

 are always attached, is usually a narrow piece running parallel with 

 and joined to the outer side of the maxilla at the base. 



Lacinia (the blade). This is the chief part of the maxilla. It is 

 situated above the stipes, is usually of an elongated pointed form, and 

 furnished with bristly hairs along its inner margin, and generally 

 has one or more pointed claws at the extremity : these claws are 

 called the Ungues. The name Lacinia is applied to this part by Mr. 

 M'Leay, and according to Kirby it is the Lobus Inferior. 



Galea (the helmet), or the Lobus Superior of Kirby, is a lobe which 

 is attached to the palpifer, and lies between the galea and the 

 maxillary-palpi. It is jointed in the predaceous beetles, and resembles 

 a palpus. 



* Mr. Newman has applied a new name to this part without sufficient reason, 

 ince it is well defined by Kirby. The name insertio is also objectionable, 

 since it might create confusion, the same name having been also applied by 

 Mr. Newman to a part of the labium. 



t By the same rule that we do not apply the name labium both to the whole 

 labial apparatus and at the same time to a part, we reject the name maxilla as 

 applied to a part of the maxillary apparatus. 



