PHYSIOLOGY OF INSECTS. 115 



the possession of feelers ; they are divided by 

 sutural lines into four parts, the insertion, the 

 disk or stalk, the feeler-bearer, and the blade. 

 They also bear the helmet and maxillary feelers. 



408. The insertion (insertio) is mostly hidden 

 by the neighbouring portions of the skull when 

 the maxilla is at rest ; but, on the least motion, a 

 portion of it becomes visible on each side of the 

 lower lip ; it is of softer and more cartilaginous 

 substance than the part which succeeds it. 



409. The disk or stalk of the feeler-jaw (max- 

 illa), is divided from the inserfon by a sutural 

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

 tions. 



410. The feeler-bearer (palpifer) is usually 

 placed above the stalk of tbe 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 know- 

 ledge of these parts is not essential to accurate 

 generic description, their variation being less 

 available than those of the succeeding portions 

 of the feeler-jaw. 



411. The blade of the feeler-jaw (lacinia) is 

 its apical portion, and its variations are of great 

 importance, for on them the great divisions of 

 insects are principally founded. 



412. A convolute blade of the feeler-jaw 

 (lacinia convoluta) is when it is rolled up below 



i 2 



