[ 188 ] 



lbalf^an^1l3our at tbc fIDicroecope, 

 TRUitb /llbr. ITutfen Meet, df.X.S,, ff.1R»/IC).S,, etc. 



Plate 19. 



Lady-Bird, Mouth of.— A few words about the composition of 

 the vwidh in insects. It will be best said in Professor Westwood's 

 words, as they cannot be improved upon, and they enable me to 

 understand it as I had never done before : — 



"The Organs of the Mouth are, notwithstanding all their 

 variety of form, reducible to one type of structure. They consist 

 of six principal organs, of which four are lateral and disposed in 

 pairs ; the two others are opposed in the opposite direction, thus, 

 ■ filling up the space left by the two other pairs, above and 



■ ■ beneath. The upper single piece is the upper lip (labrum) ; 

 " ■ '' the upper lateral pair of organs are the mandibles or upper 

 jaws ; the lower lateral pieces are the maxillae or lower jaws ; and 

 the under single piece is the under lip. The three lower organs 

 are furnished with articulated appendages (palpi). 



" The first principal variation in the structure of the mouth 

 originates in the mode of action of the various organs. Thus, 

 when the lateral pieces are short, inserted at a distance apart, and 

 have a horizontal motion, the action is that of biting ; when, on 

 the other hand, the lateral pieces are elongated, originating near 

 together, and having a longitudinal motion, the action is that of 

 sucking, the ascension of fluids in the latter case being produced 

 by the gradual approximation of the pieces of the mouth, which 

 thus form a syphon or haustellum " (" Modern Classification of 

 Insects," page 8). 



The figures will, it is hoped, serve to illustrate the above 

 quotation. I must ask those of our members who are familiar 

 with these subjects to bear with me in the endeavour to simphfy 

 them. All have not had equal advantages, and the special design 

 of these remarks is to smooth over the difficulties which beset all 

 beginners. 



Master the parts of the mouth in this species, and we shall be 

 ready to discuss forms more difficult to understand as they come 

 under our notice. 



EXPLAJSATION OF PLATE XIX. 

 Fig. 1. — Head of Changeable Lady-bird. 



j^ 2— 5.— Parts of the mouth dissected and arranged so as to build 

 up a model of the head. 



