EXTERNAL ANATOMY OF INSECTS. 453 



the liquid V M. Lamarck thinks that the labium of 

 insects has a vertical motion (de haul en has ou de has 

 en haut) b . This it certainly has in some degree; but it 

 has also, as in the above case, a more powerful horizon- 

 tal one, which is produced, in Hymcnoptera at least, 

 by the opening of the maxillae — as I have already ob- 

 served c . 



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 labium 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 d . In Stenus this organ is retractile, and consists 

 of two joints e . 



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 

 its various configurations : — in the bees it is very long, 

 in most other insects very short. Though frequently 

 simple and undivided, in many cases it presents a diffe- 

 rent conformation. Thus in the saw-flies ( Tenthredo L.) 



• l Huber Fourmis, 4—. b Anim. sans Vertebr.m. 304. 



c See above, p. 440. '• Reaum. v. 309 — . 



- Plate XXVI. Fig. 23. i Clairv. Ent. Helvet. ii. Pref. xxii. 



