EXTERNAL ANATOMY OF INSECTS. 433 



in proportion to their thickness, than they are in those 

 which use them principally for mastication. In the lo- 

 cust tribes [Locusta Leach), they are extremely thick 

 and powerful organs, and fitted for their work of devas- 

 tation ; but in the glow-worm (Lampyris), they are very 

 slender and minute. In those brilliant beetles, the Bu- 

 prestes, they are very short ; but in the stag-beetles, and 

 those giants in the Capricorn tribe, the Prioni, they are 

 often very long a . They either meet at the summit, lap 

 over each other, cross each other, or are protended 

 straight from the head ; as you have doubtless observed 

 in the stag-beetle, whose terrific horns are mandibles of 

 this description. These organs are usually symmetrical, 

 but in some instances they are not : thus in Hister Icbvus, 

 a kind of dung-beetle, the left hand mandible is longer 

 than the right; in Creophilus maxillosus K. (Staphy- 

 linus L.), a common rove-beetle, in the left hand man- 

 dible the tooth in the middle is bifid, and in the right 

 hand one intire ; and in Bolbocerus K. the mandible of 

 one side, in some species the dexter, and in others the 

 sinister, has two teeth, and the other none. 



The next circumstance with respect to these organs 

 which demands our attention, is the teeth with which 

 they are armed. These are merely processes of the sub- 

 stance of the mandible, and not planted in it by gompho- 

 sis b , as anatomists speak, as they are in vertebrate ani- 

 mals. They have, however, in their interior, at the base 



a For Maudibles of Locusta see Plate VI. Fig. 6. c'. of Lampyris 

 Oliv. Ins. no. 28. t. If. 1 of Buprestis, Ibid. no. V>2. t. iii./. 17- of 

 Lucanus, Ibid. no. 1. 1. i— v. and of Prionus, Ibid. no. 60. t. ii./. 8. 



b Gomphosis is, when one bone is immoveably fixed in another as 

 a nail in a board. 



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