1738 THE BUTTERFLIES OF NEW ENGL/VND. 



appendage becomes the maxillary palpus, reduced to a couple of niiiuite 

 joints or even less, only to be detected by the most careful observer, and 

 jjhysialogically null. 



As this sucking mouth is one of tlie most characteristic parts of the per- 

 fect butterfly, we Mill examine it more closely. Although almost entirely 

 concealed when coiled, it is frequently as long as the entire body, and con- 

 sists of two lateral halves united down the middle ; each half is composed 

 of an immense number of short, transverse rings, which are convex on the 

 outer surface, concave on the inner (87: 23) ; and it is by the union of 

 these inner concavities that a central tube is formed. The lateral rings 

 are also partially hollow, and have, therefore, been supposed by some to 

 form the sucking tube, in which case the insect might be said to have two 

 mouths, for there would be two entrances to the oesophagus. This, how- 

 ever, is not the case, the interior of each lateral lialf being occupied by 

 muscles, tracheae, and nerves for the movement of the organ. The rings 

 of which it is composed are made up of a great number of plates, united 

 by the more yielding part of the cuticle, allowing of great freedom of 

 motion. These rings throw oft", at the points where the convex and con- 

 cave sides meet, a series of oblique, curving plates or hooks, which, when 

 the two maxillae are brought together, interlace in the most complete man- 

 ner, to form a perfectly flexible yet impervious tube. The outer walls of 

 the lateral tubes are supplied with curious papillae of greatly varying 

 shapes, size, and abundance in different groups, but, in general, more 

 highly organized and abundant in the highest family. These must 

 probably be regarded as organs of taste. Within either half of the maxil- 

 lae, oblique muscles exist (87: 9), serving to coil the whole into the watch- 

 spring-like form in which it is packed away when at rest. 



But now that we comprehend the structure of this wonderful piece of 

 mechanism, and can appreciate the change that has been wrought in its 

 development from an utterly simple, almost microscopic joint, do we un- 

 derstand any better its actual use in extracting honey from flowers ? Some 

 have thought that the upward flow was due to capillary motion ; some to 

 the action of the so-called sucking stomach, a sac-like expansion of the 

 alimentary canal just in advance of the true stomach ; others that it is 

 forced on by successive undulations and contractions of the tube itself. The 

 investigations, however, of one of our own naturalists (who has more re- 

 cently distinguished himself in tlic construction of the swiftest yachts in 

 the world) has lately shown the existence of a muscular sac within the 

 head (87: 5) at the origin of the alimentary tract, furnished with a valve at 

 its front extremity where it opens into the maxillary canal. AVhen the 

 radiating muscles running from the walls of the head to the periphery of 

 this sac are contracted (87:3), the sac is opened, and into the vacuum 

 thus produced the fluids into which the maxillae tips are plunged ascend. On 



