ENTOMOLOGY. 117 



Ephemeridic and Libellulidae, are of this de- 

 scription. 



As this hasty and imperfect sketch of water- 

 insects may serve to shew the small space they 

 occupy in the sixteen modem orders, it may, 

 perhaps, hold out an encouragement to the 

 young entomologist to pay more attention to 

 their investigation. "* 



The manner in which they deposit, and the 

 very high specific gravity of some of, their eggs, 

 seem to have escaped the notice of our best 

 authorities. 



Swammerdam states, that " the eggs of the 

 ** female Ephemera drop into water, and there 

 " impregnated, gradually sink to the bottom.*' 

 A little attention to this interesting family will, 

 however, convince any enquirer that this is not 

 the case with the Ephemeridae of the Derbyshire 

 rivers. 



I apprehend, there is also a remarkable cir- 

 cumstance connected with the separation of the 

 eggs from the female, which, I am not aware, 

 has been any where noticed, viz. they are not 

 ejected, as by most insects, from the caudal ex- 

 tremity, but between the second and third rings 



