

i6 



HYMENOPTERA 



invaginated part can be thrust out by increase of the pressure of 



the fluid in the tube. A portion 

 of the wall of the invaginate part 

 is thickened so as to form a chiti- 

 nous rod. 



This description will suffice for 

 present purposes, as the other parts 

 of the mouth will be readily re- 

 cognised by the aid of figure 9, A, 

 B, C. In the exquisitely endowed 

 South American genus Euglossa (Fig. 

 18), the proboscis is somewhat longer 

 than the whole of the body, so that 

 its tip in repose projects behind 

 the body like a sting. 



The correct nomenclature of the 

 parts connected with the lower lip 

 is not definitely settled, authorities 

 not being agreed on several points. 



FIG. 8. -Transverse section of ligula The whole of the proboscis is usually 



of honey-bee, diagramatic. A, called the tongue ; this, however, is 



With the long sac invaginate. B, , . , , , . 



evaginate : a, chitinous envelope admittedly an erroneous application 

 with the bases of the hairs ; b, o f this term. The terminal deli- 

 rod ; c, groove of rod ; d, lumeu . 



due in A to invagination of the cate, elongate, flexible organ is by 



rod, in B to its evagination ; n, some called the tongue ; bllt this 

 nerve ; tr, trachea. 



again is wrong : the lingua in 



Insects is the hypopharynx ; this part is developed in a peculiar 

 manner in bees, but as it is not tongue-like in shape, the term 

 lingua is not suitable for it, and should be dismissed altogether 

 from the nomenclature of the bee's trophi ; it is used at present 

 in two different senses, both of which are erroneous. We see no 

 objection to describing the flexible apical portion of the proboscis 

 as the ligula. The lorum is probably a special part peculiar to 

 the higher bees ; according to Saunders it is not present as a 

 specialised part in some of the primitive forms. 1 The application 

 of the terms mentuin, submentum and hypoglottis is open to the 

 same doubts that exist with regard to them in so many other 



1 For figures and descriptions of the proboscides of British bees, refer to E. Saun- 

 ders, Jour. Linn. Soc. xxiii. 1890, pp. 410-432, plates III.-X. : and for details of 

 the minute structure and function to Cheshire, Sees and Sec-keeping, vol. i. 



