INSECTS: THEIR MOUTHS 181 



and that this point is double, for it is frequently seen 

 separate a considerable way up. Hence you would prob- 

 ably infer that the organ consists of two equal and con- 

 similar halves, united longitudinally. And so, indeed, 

 it does; and these halves are the representatives of the 

 maxillce or lower jaws of the Beetle, being thus greatly 

 developed at the expense of almost all the other parts. 

 The upper lip and the mandibles are discernible only in 

 the form of three most minute plates; the labial palpi are 

 large and prominent those well-haired points that project 

 in front of the head, one on each side of the spire. This 

 spiral form of the maxillce is called anilia. 



It is not, however, very easy to fix it in an extended 

 condition on a slip of glass, so as that it shall lie flat 

 throughout its whole length, without injuring the parts 

 or so agglutinating them together that their structure is 

 concealed or distorted, and in either case unfitted for mi- 

 croscopical examination. The specimen which I have pre- 

 pared, from the mouth of the Small Garden White Butter- 

 fly, is stretched, and fixed in balsam, and will, I think, 

 show you the structure under a high power very well. 



Before we examine it, however, I will cite you the de- 

 scription of one of the most eminent of microscopical anat- 

 omists, Mr. Newport. He considers each maxilla to be 

 composed of an immense number of short transverse mus- 

 cular rings, which are convex externally and concave in- 

 ternally, the two connected organs forming a tube. Within 

 each there are one or more large trachece, connected with the 

 trachece in the head. The inner or concave surface which 

 forms the tube is lined with a very smooth membrane, and 

 extends along the anterior margin throughout the whole 

 length of the organ. At its commencement at the apex 



