192 THE EPHEMERINA. 



very frequently) ;, without any necessity for turning 

 round. The larva is a semitransparent creature, fur- 

 nished with six legs, and with a curious series of gill- 

 plates on each side of the abdomen, which from their 

 transparency afford an excellent means of witnessing 

 the circulation of the blood in an insect. The 

 body, which has some resemblance to that of the 

 perfect insect, is terminated by three short tails 

 fringed with delicate hairs, and, as if to make up for 

 the abbreviation of these appendages, the antennae 

 are considerably longer than in the perfect insect, 

 and the mandibles are provided with long horn-like 

 processes, which project in a most formidable manner 

 from the front of the head. The pupa presents 

 nearly the same form and structure as the larva, but 

 exhibits the rudiments of wings upon the back of the 

 thoracic segments. During these preparatory stages, 

 which are supposed to occupy at least two years, the 

 insect lives for the most part in concealment ; and by 

 some entomologists who have always found mud in 

 its intestines, it has been conjectured that it derived 

 its nomishment from vegetable matters which might 

 be mixed up with the soft mud; but I am more 

 inclined to think that it feeds upon minute aquatic 

 animals, of which plenty might be obtained without 

 quitting its burrow. 



Whatever may be the nature of its diet in its larva 

 state, it is little troubled with procm-ing sustenance 

 when arrived at maturity, for its entire existence after 

 arriving at the dignity of wings is limited to a few 

 hours : its whole business consists in providing for the 

 continuation of its species; it requires no nom^ish- 

 ment, and the organs of its mouth are accordingly 

 reduced to the merest rudiments. 



i 



