INTRODUCTION. XXXV11 



rated throughout their whole length.* Each of these pieces is 

 traversed longitudinally by a cylindrical tube, and being 

 grooved on their inner side> they form, when united, another 

 canal in the centre, of a somewhat square form, and wider than 

 either of the two lateral ones. The junction of the two pieces 

 is so close that the enclosed tube is perfectly air-tight, and 

 this union is effected by means of an infinite number of filets, 

 resembling the laminae of a feather, which interlace and 

 adhere to each other. Of these three tubes, the central one 

 alone serves for the influx of the alimentary fluids, the two 

 lateral ones being probably employed in transmitting air in aid 

 of respiration,! which, however, is mainly carried on by means 

 of stigmata or lateral pores. The outer extremity of the pro- 

 boscis is frequently beset with many membranous papillae, 

 resembling leaflets, which have been regarded by some authors 

 as absorbents. From having observed them chiefly in long 

 and slender trunks, Reaumur was led to conceive that their 

 only use is to render that organ more steady, by affording 

 numerous points of support, and adhering in some degree to 

 the substance into which it is inserted an explanation rendered 

 highly probable by the fact that the long and slender ovipositors 

 of Ichneumons, and many other insects, are generally provided 

 with some pointed projections near the tip, evidently intended 

 for this purpose. Several of the figures on Plate I. are designed 

 to illustrate the structure of the organ just described. Fig. 9 

 is a magnified view of the trunk, showing its general form, and 

 the projecting points near the tip (a) Fig. 10, is a highly-mag- 

 nified section, exhibiting the two portions (a, b), of which it is 

 composed, each of them tubular (c, d\ and forming by their 

 junction a central canal (e). Fig. 1 1 is another section, repre- 

 senting the under side. 



In fresh specimens of some of the larger Lepidoptera this may easily be 

 done with a fine needle. 



f More probably, to facilitate the pumping up of fluids into the mouth. 



