76 Objects for the Microscope. 



state feed on decayed vegetable matter, which else would 

 render the air unwholesome for our existence, and more 

 offensive to our senses than can well be imagined. Let us 

 examine, therefore, the mouth of our little scavenger. 



It has six parts. An upper lip, called labrum, which covers 

 the mouth, and is horny or leathery, but simple in form. 



Two upper jaws, 'called mandibles, varying in shape, but 

 strong and toothed, or hooked, for seizing their prey and 

 tearing it to pieces before it is passed on to the more deli- 

 cate under jaws or 



Maxillae, which are fringed with delicate hairs, and to 

 which are attached jointed palpi, or feelers. The tips of 

 these are often triangular, or hatchet-shaped, which will 

 distinguish them for your observation. These palpi move 

 very rapidly, apparently examining the food, and two others 

 are attached to the under lip or 



Labium, for the same purpose. Part of the labium is 

 called the chin or mentum, usually having a notch in the 

 centre. Some of the Beetles have a distinct tongue inside 

 all this the Dung-beetle for instance lying between the 

 labium and labrum. It is a simple membrane, sometimes 

 fleshy, sometimes horny. 



The mouth of a Beetle would be much better examined 

 by taking a large Beetle, and soaking the head for a few 

 days in liquor potassaB ; then washing it in a watchglassful 

 of water, when the parts are easily separated and studied. 

 Do this, because from one mouth we cannot learn all that is 

 useful or interesting. For instance, in the mandibles are 

 found different kinds of teeth ; molar teeth for grinding 

 food, or incisive teeth for tearing it. The maxillae also 

 vary extremely in their form and appendages. The lobes 

 are often furnished with spines or teeth, and are single or 

 double, fringed or plain ; but the predaceous Beetles have 

 always fringed lobes like stiff brushes, as if for cleansing 

 the food or the other appendages of the mouth. Also, I 

 may mention that the palpi of those Beetles which feed 

 on the pollen of flowers, such as the tribe of the Nitidu- 

 sidce, are used by them to open the anthers in a very 

 curious way. 



