EXTERNAL ANATOMY OF INSECTS. 417 



cibaria, the name Fabricius gave them, I shall call tropin 

 or feeders. It is upon these parts, you are aware, that 

 the system of the celebrated Entomologist just mentioned 

 is founded; and could they always, or even for the most 

 part, be inspected with ease, they would no doubt afford 

 characters as various and discriminative as those of the 

 vertebrate animals. Differences in these parts indicate 

 a difference in the mode in which the animal takes its 

 food, and often in the kind of food, and sometimes in its 

 general economy and habits, — circumstances which are 

 powerful and weighty in supporting the claim of any set 

 of animals to be considered as forming; a natural genus 

 or group. Trifling variations, however, of these parts, 

 unless supported by other characters and qualities, ought 

 not to have much stress laid upon them, since, if we in- 

 sist upon these, in some tribes almost every species might 

 be made a genus. 



With respect to their trophi in general, insects of late 

 have been divided into two great tribes a , masticators and 

 suckers j t\\e.Jlrst including those that are furnished with 

 instruments to separate and masticate their food; namely, 

 an upper- and under-lip (lahrum and labium), upper- and 

 under-jaws {niandibula and maxillce), labial and maxil- 

 lary palpi, and a tongue {lingua) : and the second those 

 in which these parts are replaced by an articulate or ex- 

 articulate machine, consisting of several parts and pieces 

 analogous to the above, which pierce the food of the ani- 

 mal, and form a tube by which it -sucks its juices. If, 

 however, the mode in which insects take their food be 



» Clairville {Ent. Helvet. i. 44) appears to have been the first \vh© 

 classed insects according to their mode of taking their food. 

 VOL. III. 2 E 



