104 



INTRODUCTION TO ZOOLOGY. 



From the diversity of their food, and the great variety ot 

 circumstances under which it is obtained, we naturally expect 

 considerable modification in the structure of the mouth and its 

 appendages — in other words, of the instruments by which the 

 food is obtained; and, accordingly, we find it is sometimes 

 furnished with' jaws for cutting and for masticating sohds, 

 and, at other times, with tubes of very different kinds, 

 adapted for the imbibing of fluids, such as the blood of 

 animals, the honey of flowers, or the sap of growing plants. 

 Before noticing this admii-able variety of structui^e, in con- 

 nexion with the habits of different insect tribes, it may he 

 well to acquire distinct ideas of the parts of which the mouth 

 is composed. 



The mouth of one of the rapacious Beetles (Fig. 8], Carahus\ 

 which are constantly crossing our path in quest of prey, AviU 

 afford a familiar example. It consists of seven parts {Fig. 82). 

 An upper lip (labrum) ; a lower lip (labium) ; a tongue (lingua) ; 

 two upper jaws (mandibulce); and two lower jaws (maxillcB). 

 The motion of the jaws is nut vertical, as in the vertebrate 

 animals, but is horizontal ; and the lower jaws are sometimes 



c:::? 



Fig. 81.— Carabus. Fig. 82.— Parts of Mouth of Carabus. 



employed in holding the food which the upper jaws or man- 

 dibles are engaged in cuttmg to pieces. In some orders the 

 seven parts are not to be seen with such distinctness, some of 

 them being prodigiously enlarged, and others diminished, or 

 perhaps altogether wanting. 



Fig. 82 — o, Labrum. -d, Labium — 6, Mandibles.— c, MaxilljB. The feelers 

 attached to the Maxillae are called AtaxiUary palpi; and those to the Labium, 

 tiolual palpi. 



