PIIYSIOLOOY OK 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 insertion 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 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 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 (laeinia) 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 

 {laeinia convoluta) is when it is rolled up below 



