EPHEMERA. 23 



are excluded at the same moment, and fall to- 

 gether in one mass upon the water. Provi- 

 dence, ever ready to supply deficiencies, where 

 those deficiencies may prove injurious to its 

 creatures, has provided this little insect with 

 a couple of small bladders, which it has the 

 power of filling with air immediately after the 

 exclusion of the eggs. Without such provision, 

 which gives it the means of restoring the equi- 

 librium, a vacuum so suddenly formed, might 

 prove fatal to the Ephemera. 



SPECIFICATION. 



Ephemera vulgata. Ep.cauda triseta, alls nebu- 

 loso-maculatis. Linn. Syst. Nat. 1 . p. 906. Gmel. 

 p. 2623. Fair. Ent. Syst. %p. 68. Spec. Ins. 1. 

 p. 383. Mant. Ins. 1. p. 243. 

 Degeer, Ins. 2. 1. 16. f. 1. 

 Schaeff. Icon. Ins. t. 9.f. 5, 6. 

 Panzer, Faun. Ins. Germ.fasc. 04. 1. 16. 

 Inhabits Europe. The larva is found in the wa- 

 ter ; the perfect insect in the trees and bushes On the 

 banks. 



