118 GRAMMAR OF ENTOMOLOGY. 



immediately below the upper lip, and immediately 

 above the feeler-jaws, one on each side of the 

 mouth, meeting, and sometimes crossing in front : 

 when possessed of motion, they move hori- 

 zontally. 



424. Rudimental mandibles (mandibulce inci- 

 pientes) are those which are perfectly without 

 motion, and, apparently, without use ; they are 

 small scale-like processes adhering to the skull, 

 and are utterly incapable of gnawing solid sub- 

 stances : they have this form in butterflies. 



425. Linear mandibles (mandibulce lineares) 

 are those which are of uniform size and sub- 

 stance ; which are perfectly straight, parallel, and 

 approximate ; they are always without the hori- 

 zontal motion, and utterly incapable of gnawing 

 solid substances : they have this form in many 

 flies. 



426. Tubulate mandibles (mandibulce tubu- 

 latce) are those which are hollow, and perforated 

 at the extremity to admit the passage of the 

 blood of other insects, on which the insects pos- 

 sessing such mandibles always feed : the man- 

 dibles possess this form in the larvae of some 

 carnivorous beetles, and in that of the ant-lion. 



427. Falciform mandibles (mandibulce falci- 

 formes) are when they are long and much curved, 



in the shape of a sickle ; they move horizontally 

 with great ease, are hard and acute, and, when 

 closed, cross each other: insects possessing these 



