INSECTA. 



259 



stores are lodged. When unfolded, the apparatus in question repre- 

 sents a long double whip-lash (Jig. 115, a, 5, c, d), and, if carefully 

 examined under the micro- 



scope. 



each division is found 



Fig. 115. 



to be made up of innumer- 

 able rings connected toge- 

 ther, and moved by a dou- 

 ble layer of spiral muscular 

 fibres, that wind in oppo- 

 site directions around its 

 walls. When not in use, 

 the proboscis is coiled up 

 and lodged beneath the 

 head ; but when uncurled 

 its structure is readily ex- 

 amined. Each of the two 

 long filaments composing 

 this trunk, which, in fact, are the representatives of the maxilla: 

 excessively lengthened, is then seen to be tubular ; and, when they 

 are placed in contact, it is found that their edges lock together by 

 means of minute teeth, so as to form a central canal leading to the 

 orifice of the mouth. It is through this central tube, formed by 

 the union of the two lengthened maxillae, that fluids are imbibed. 

 Burmeister, however, asserts that the cavities contained in each divi- 

 sion likewise communicate with the commencement of the oasophagus, 

 so that the Lepidoptera have, as it were, two mouths, or rather two 

 separate methods of imbibing nourishment ; one through the com- 

 mon canal formed by the junction of the whip-like jaws, the other 

 through the cavities of the filiform maxillse themselves : such an 

 arrangement, however, which would be quite anomalous, may rea- 

 sonably be doubted. In this mouth, therefore, all the parts, except 

 the maxillse, would seem at first sight to be wanting ; they may, 

 nevertheless, be detected upon a very careful examination, and 

 rudiments of the upper lip, of the mandibles, of the lower lip, as 

 well as of the labial and maxillary palpi, be distinctly demonstrated. 

 (300.) The last kind of mouth to which we shall advert, is that 

 met with in the louse tribe (Pediculi) ; but, from the extreme mi- 

 nuteness of the parts composing it, the details of its structure are 

 but imperfectly known. It seems to consist of a slender external 

 tube, wherein a sharp sucker, armed with barbs adapted to fix it 

 securely during the act of sucking, is lodged ; when feeding, the 



