442 SUPPLEMENT 



applying there the posterior extremity of their body, where 

 the organs of respiration are situated. They keep thsm 

 even on a level with the water when they are in a state 

 of repose. They then hook themselves to aquatic plants, 

 and often one to another, extending themselves horizontally. 

 Those which the naturalist, just mentioned, reared, never 

 fought amongst themselves. They lived on aquatic insects, 

 and particularly on water^snails, to which they are very 

 partial. Lyonnet has observed that their head is a little 

 inclined backwards, to enable them to seize the mollusca with 

 more facility, and that .their back serves as a resting-point 

 on which to break the shell, and a table on which to eat the 

 animal. After having seized it with their mandibles, they 

 bend themselves backwards, raise the back a little, and rest 

 the snail upon it. In this attitude, with their head a little 

 turned, it bears more perpendicularly on the shell, which 

 gives them a greater facility in breaking it, and then eating 

 the animal. 



M. Mister confirms the truth of these observations. He 

 has given to these larvae some small pieces of raw meat, on 

 which they have lived during a longer space than fifteen days. 



When they are on the point of passing into the nymph 

 state, they issue from the water, gain the shore, and employ- 

 ing their mandibles and feet, they dig for themselves in the 

 earth an almost spherical cavity, very smooth, about eighteen 

 lines in diameter, and presenting no aperture. Their body, 

 in this retreat, is placed upon the belly, and curved into an 

 arch. They still preserve their form for about the space of 

 ten days. Their skin afterwards opens on the back, as far as 

 the fourth ring, commencing from the head, and the nymph 

 thus makes itself a passage. It is thirteen or fourteen lines 

 in length, whitish, terminated by forked appendages, and 

 presents, at each of the anterior angles of its corslet, an 

 aigrette of three corneous and recurved hairs. Its body, the 



