452 EXTERNAL ANATOMY OF INSECTS. 
moving itself forwards in conjunction with the lower 
jaws: and when the insect wishes to lap, all this appa- 
ratus moves forward; so that the tongue, which is very 
short, does not require to lengthen itself much to reach 
the liquid.” M. Lamarck thinks that the labcum of 
insects has a vertical motion (de haut en bas ou de bas 
en haut)”. ‘This it certainly has in some degree; but it 
has also, as in the above case, a more powerful horzzon- 
tal one, which is produced, in Hymenoptera at least, 
by the opening of the maxilla—as I have already ob- 
served °. 
I have little to say with respect to the structure of the 
tongue: it generally seems to be without articulations ; 
but in many bees it articulates with the /abzwm where it 
enters it, so as when unemployed to form a fold with it. 
In the hive-bee it terminates in a kind of knob or button, 
which has been falsely supposed to be perforated for im- 
bibing the honey by suction. The upper part of this 
tongue is cartilaginous, and remarkable for a number 
of transverse rings: below the middle, it consists of a 
membrane, longitudinally folded in inaction, but capa- 
ble of being inflated to a considerable size: this mem- 
branous bag receives the honey which the tongue, as it 
were, laps from the flowers, and conveys it to the pha- 
rynx%, In Stenus this organ is retractile, and consists 
of two joints *. 
The shape of the tongue of insects probably varies as 
much as any other part; but as it is apt to shrink when 
dried f, and is not easy to come at, we know but little of 
* Huber Fourmis, 4—. > Anim. sans Vertébr. 111. 304. 
© See above, p. 439. “ Reaum, v. 309—. 
© Pirate XXVI. Fic. 23.  Clairv. Ent. Helvet. ii. Pref. xxii. 
