EPHEMERA MARGINATA. 65 



to a power sufficiently high to discern these extremely 

 delicate and transparent tissues; and even then, to see 

 them to the greatest advantage, recourse should be had 

 only to such as are in the last three or four sections of 

 the body." 



When the larva is dead, the particles of the blood, of 

 an oblong figure, may be distinctly discerned in its forked 

 tail ; and their motion is perceptible in the limbs for 

 nearly an hour after they are separated from the body. 

 These particles, like those of the human blood, assume a 

 spherical form when mixed with water. 



The peristaltic motion of the alimentary canal will also 

 present, under a good instrument, a beautiful and inte- 

 resting appearance. 



The three-pronged tail of this insect, in its advanced 

 age, is beautifully fringed with clusters of fine, straight, 

 smooth hairs or bristle?, several in each bunch, as re- 

 presented in fig. 4. As the time for its transformation 

 approaches, the central prong of the tail becomes more 

 transparent, and assumes the appearance of a jointed 

 tube, or shell-like case ; while the two exterior ones dis- 

 tinctly exhibit portions of the tail of the perfect insect 

 inclosed within them, as shewn in the drawing. The 

 same may be observed as to the legs, which are seen to 

 contain those of the perfect fly. 



This larva is produced from an egg, deposited by the 

 perfect insect in the waters of pools or ditches, among 

 duck-weed and the water-grasses. Its disposition is mild 

 and inoffensive. It is incapable of destroying creatures 



