OF GYRINUS. 9 3 



my good fortune, on one occasion, to observe an in- 

 dividual of a different species in an unusual situa- 

 tion — the inhabitant of a freshwater shell (Limneus 

 pereger). When the shell was taken out of the 

 pool, its mouth was filled with what appeared a 

 mass of clay, but proved to be a fragment of some 

 aquatic plant of suitable length, the space between 

 it and the margin of the aperture being filled with 

 slime. The interior of this mass was lined with a 

 soft, whitish, silky substance, which extended to 

 the edge of the aperture. The " hollow- wreathed 

 chamber" of the shell was occupied by a living indi- 

 vidual of Gyrinus vUlosus, an insect which, I believe, 

 had not previously been taken in this neighbourhood. 

 Its habits are solitary, being the very rcA'erse of those 

 of its merry little congener, the Gyrimis natator. 

 Your observation would, perhaps, ascertain if those 

 species undergo their transformation in different situ- 

 ations, — if the one is always to be found beneath the 

 water, while the cocoon of the other is suspended 

 to the stem of some aquatic plant. Or you could, 

 perhaps, prove, that in the present instance the in- 

 sect, when about to undergo its transformation, had 

 probably taken advantage of an empty shell which 

 chance had thrown in its way, and had thus been 

 saved the trouble of constructing the customary 



