162 



PHYSIOLOGY OF INSECTS. 



the part which succeeds it. The disk or stalk of the 

 feeler-jaw or maxilla, o2, is divided from the insertion by 

 a sutural line ; it is hard, glabrous, and of various forma- 

 tions. The feeler-bearer or palpifer, o3, is usually placed 

 above the stalk of the feeler-jaw, but is often parallel with 

 it, thus constituting its exterior portion ; in either case it 

 is a solid corneous part, and distinctly divided from the 

 stalk by a sutural line. It may be useful to observe, that 

 a knowledge of these parts is not essential to accurate 

 generic description, their variations being less available 

 than those of the succeeding portions of the feeler-jaw. 

 The blade of the feeler-jaw or lacinia, o 4, is its apical 

 portion, and its variations are of great importance, for on 

 them the gTeat divisions of insects are principally founded. 

 A convolute blade of the feeler-jaw or 

 lacinia convoluia, is when it is rolled 

 up below the head in the manner of 

 the main-spring of a watch, or the 

 Ionic volute in architecture. When 

 bearing this form it is exceedingly 

 long, slender, and pliable ; and the 

 Feeier.jawsofaMoth. bladcs of cach fccler-jaw being in- 

 ternally grooved, unite and form a honey-sucking^ tube : 

 it has this form in butterflies and moths. A lanceolate 

 blade or lacinia lanceolata, is when it is straight, flat, de- 

 creasing gradually to a sharp point, incapable of any hori- 

 zontal motion, and employed by being thrust vertically 

 into the object on which its possessor feeds : it has this 

 foi-m in blood-sucking gnats and flies. A leathery blade 

 or lacinia coriaria, is when it is composed of a tough, 

 strong, and flexible substance ; when this is the case, it 

 usually is very long, without horizontal motion, parallel 

 with the ligula, and unites with that part of the mouth in 

 forming a sucking tube: it has this form in bees. An 



