ON ARACHNIDA. 441 



position vary according to the manner in which these 

 animals hold themselves in a state of repose, and according 

 to some peculiar habits. They are very brilliant, and in 

 some species offer the appearance of a pupil and an iris. 



The organs of manducation occupy the anterior and lower 

 extremity of the trunk. They consist of two mandibles, two 

 palpi, a lip, and a kind of epiglottis, or interior tongue. The 

 mandibles advance in parallel directions, and are composed of 

 two tubular articulations, the first of which is the largest, and 

 the terminal one more solid and scaly, in the form of a very 

 sharp crook, and having at its extremity a small cleft, destined 

 for the passage of a poisonous fluid, which is conducted thither 

 by an interior canal, from the base of the first articulation, 

 where its reservoir, or the poisonous receptacle exists. The 

 palpi, like little feet, especially in mygale, are of the same 

 thickness, or filiform, in the females, thicker at their extremity 

 in the males, and composed of five, or even six, articulations. 

 The jaws are composed of a single piece, in the form of a 

 lamina, more or less oval and triangular. The palpi articu- 

 late with their summit in the mygale, so that the jaws in 

 reality form the first articulation. However, in the other 

 araneides, it is at the base of their internal side, that the 

 palpi are inserted. The lip is also of a single piece, the 

 figure of which most usually approaches a square, or an oval, 

 truncated at its base, and is but an appendage of the anterior 

 extremity of the breast. The interior of the mouth, or palate, 

 presents a fleshy piece, hairy, in the form of a tongue, which, 

 in most of the sp'ecies, is applied against the internal surface 

 of the lip. There is, probably, on each of its sides, an aper- 

 ture for the passage of the alimentary fluids. The mandibles, 

 no doubt, contribute to manducation ; but though hollow and 

 pierced at their extremity, they do not perform the office of a 

 sucker. Their use is to retain the insect seized by the 

 araneid, and facilitate the compression made upon it by the 



