668 



INSECTS AND ARACHNIDA. 



Fig. 289. 



and which, being pre-eminently adapted for suction, is termed 

 the haustellate mouth. In these insects, the labrum and mandi- 

 bles are reduced to three minute triangular plates ; whilst the 

 maxillae are immensely elongated, and are united together along 

 the median line, to form the haustellium or proboscis, which con- 

 tains a tube formed by the junction of the two grooves that are 

 channelled out along their mutually applied surfaces, and which 

 serves to pump up the juices of deep cup-shaped flowers, into 

 which the size of their wings prevents these insects from enter- 

 ing. The length of this haustellium varies greatly ; thus in such 

 Lepidoptera as take no food in their perfect state, it is a very in- 

 significant organ ; in some of the white Hawk-moths, which 

 hover over blossoms without alighting, it is nearly two inches in 

 length ; and in most Butterflies and Moths it is about as long as 

 the body itself. This haustellium, which, when not in use, is 

 coiled up in a spiral beneath the mouth, is an extremely beautiful 

 microscopic object, owing to the peculiar banded arrangement it 

 exhibits (Fig. 289), which is probably due to the disposition of 



its muscles. In many 

 i n stances, the two halves 

 maybe seen to be locked 

 together by a set ot 

 hooked teeth, which are 

 inserted into little de- 

 pressions between the 

 teeth of the opposite 

 side. Each half, more- 

 over, maybe ascertained 

 to contain a trachea or 

 air-tube (§ 391) ; and it 

 is probable, from the ob- 

 servations of Mr. ISTew- 

 port,' that the sucking 

 up of the juices of a 

 flower through the haus- 

 tellium (which is accomplished with great rapidity) is eifected by 

 the agency of the respiratory apparatus. The proboscis of many 

 Butterflies is furnished, for some distance from its extremity, 

 with a double row of small projecting barrel-shaped bodies (shown 

 in Fig. 289), which are surmised by Mr. ISTewport to be organs 

 of taste. Numerous other modifications of the structure of the 

 mouth, existing in the dift'erent tribes of Insects, are well worthy 

 of the careful study of the Microscopist ; but as detailed descrip- 

 tions of most of these will be found in every systematic treatise 

 on Entomology, the foregoing general account of the principal 

 types must suffice. 



388. Parts of the Body. — The conformation of the several 

 divisions of the Alimentary Canal presents such a multitude of 



' " Cyclopasdia of Anatomy and Pliysiology," vol. ii, p. 902. 



Hauslellium (proboscis) of Vanessa. 



