INSECTA. 



899 



Fig. 376. 



Lateral view of the mouth of Anthophora. Letters 

 and figures as before. 12, the lingua, or tongue. 



derable length in Anthophora. In each in- 

 stance it is broadest at its articulation with 

 the stipes, and, passing backwards diagonally, 

 unites at its extremity with a corresponding 

 part of the opposite side, and the two thus 

 joined articulate with the narrow sub-mentum, 

 the fulcrum of Kirby. The stipes forms the 

 lateral basilar part of the maxilla, and is shorter 

 in Anthophora than in Bombus, in which it is 

 about one-third of the length of the maxilla. 

 The pfilpijer is also distinct (3). The lacinia (5) 

 is of great length, and gradually tapers to its 

 extremity. Internally it is slightly concave, 

 and externally is covered with a few scattered 

 hairs. It is articulated freely with the stipes 

 and palpifer, upon which it is inflected in a 

 state of rest to form a sheath for the labium, 

 when the parts of the mouth are folded. When 

 the maxillae are extended to form the sucking 

 tube with the labium, they are a little separated 

 at their base, and inclose between them the 

 cavity of the mouth, within which is a soft 

 fleshy body, the lingua (12) or true tongue, 

 situated anterior to and serving as a valve to the 

 pharynx. The sub-mentum (m) is articulated 

 by a single joint with the united extremities of 

 the two cardines (13). It is long and narrow 

 in Anthophora, but short and triangular in 

 Bombus. It is attached at its sides by a fine 

 membrane to the under surface of the head and 

 throat. The mentum (/) articulates with the 

 sub-mentum, and is an elongated rounded plate, 

 which forms internally a channelled passage 

 to the pharynx. Within it are inserted the 

 muscles of the labial palpi (/c). These organs 

 are long and styliform, and arise from a space 

 at the base of the ligula, the part described as 

 the palpiger by Newman. Their great length 

 is occasioned by an excessive elongation of the 

 second basial joint, which is sometimes as long 

 as the whole maxilla itself, and is furnished at 

 its distal extremity with a minute brush of 

 hairs, and also articulates with the remaining 



short joint of the organ. The .remaining por- 

 tion of the labium is divided into three parts. 

 The two lateral ones are short styliform pro- 

 cesses, the paraglosstf (**), and the central one, 

 commonly called the tongue of the bee, is the 

 part employed by the insect in gathering honey. 

 In Apis, Bombus, and Anthophora it is a long 

 tapering muscular organ, formed of an immense 

 number of short annular divisions, and densely 

 covered throughout its whole length with long 

 erectile hairs. It is not tubular but solid, and 

 when actively employed is extended to a great 

 distance beyond the other parts of the mouth, 

 but when at rest is closely packed up and con- 

 cealed between the maxillae. The manner in 

 which the honey is obtained when the organ is 

 plunged into it at the bottom of a flower, is by 

 lapping, or a constant succession of short and 

 quick extensions and contractions of the organ, 

 which occasion the fluid to be accumulated 

 upon it, and ascend along its upper surface, 

 until it reaches the orifice of the tube formed 

 by the approximation of the maxillae above, 

 and the labial palpi and this part of the ligula 

 below. At each contraction a part of the ex- 

 tended ligula is drawn within the orifice of the 

 tube, and the honey with which it is covered 

 ascends into the cavity of the mouth, assisted 

 in its removal from the surface of the ligula by 

 the little brush of hairs with which the elon- 

 gated second joint of each labial palpus is fur- 

 nished. From the mouth the honey is passed 

 on through the pharynx into the oesophagus by 

 the simple act of deglutition, as in other ani- 

 mals. In Anthidium the ligula is not longer 

 than the labial palpi; while in the Andrenida 

 all the parts of the mouth are much shortened, 

 and resemble similar parts in the Vespida in 

 being divided into four lobes.* In the latter 

 insects the ligula is quadrifid, and is dilated 

 at its apex, and each lobe is terminated by a 

 minute gland.f The two lateral lobes, para- 

 glosstf, are shorter than the middle ones. In 

 Tenthredinidte the ligula is also short, but is 

 divided only into three lobes. 



We have thus seen that the head and its ap- 

 pendages are most perfectly developed as a 

 whole in the Coleoptera, and that in passing 

 through the succeeding Orders of Mandibulata 

 certain parts are more or less developed in each 

 Order, in accordance with the general habits 

 and mode of life of the insects ; that in the 

 carnivorous and omnivorous families, and in 

 those whose habits of life require a great 

 amount of strength, either in procuring their 

 food or in the construction of their nests, the 

 mandibles are the most important of the oral 

 organs, and are most largely developed. But 

 as we pass from insects with these habits to the 

 Haustellata, whose food and modes of life are 

 of an entirely different description, the man- 

 dibles lose their importance, and become atro- 

 phied, and their office, now altered in its cha- 

 racter, is performed by the maxillae and labium, 



22. 



* Newman. Paper on the Head of Insects, p. 

 t Curtis. Westwood. 



3 N 2 



