NATURAL HISTORY. 29 
that this position is never assumed by the 
animal. 
In the Libellula depressa, instead of a pair of 
forcipated jaws attached to the extremity of the 
second plate, there is a pair of triangular plates, 
each piece or plate being attached by one of its 
angles, and forming a joint, which, when closed, 
permits the opposite sides of the triangles to 
meet, and, being dentated along the sides in 
contact, they fit into each other. 
The use of this curious organ is for seizing 
their prey, a purpose which they effect with 
much caution, stealing upon it till it is com- 
pletely within their devouring grasp, then seiz- 
ing it with their fangs, and, bringing it to their 
