31 



perceiving one of them more agitated than the rest, I watched it particularly, and 

 fancied, what proved in reality to be the case, that it was casting its skin. Had 

 I not witnessed this operation, I should have been deprived of much information 

 and gratification. Notwithstanding the skin is so delicate, and when in the 

 water so purely the same colour, a close observation afforded me the opportunity 

 of collecting as many skins, during the time I was able to retain the insects alive, 

 as, I think, were thrown off. The next object that struck my attention, was the 

 appearance of a cluster of minute eggs, floating on the surface of the water, encir- 

 cled by something that had the appearance of oil ; specimens of which I placed on 

 two glasses. 



" On placing the cast skin under the microscope, I observed that each hair with 

 which the legs or paddles are provided, was thickly set on each side with a row 

 of fine hairs. I could not discover in the cast skins any portion of skin that 

 could cover the eyes ; the thin transparent membrane, therefore, that covers them 

 in the perfect insect, has no appearance of net- work, as in most other insects. 



" The insects became gradually weaker, and in four or five days they all died. 

 I took a sketch of one before it was quite dead, which I think will convey a tolera- 

 ble idea of the animal in its living state ; as those prepared as specimens on glass, 

 although very beautiful, do not, in consequence of their dried state, convey to the 

 observer a correct idea of the insect without such aid ; the cast skin assists, like- 

 wise, in its developement. 



" The circulation of the blood, with a high magnifying power, was particularly 

 interesting." 



Mr. Samouelle has subjoined the following additional observations : — " On Sun- 

 day, May 20, 1836, I caught two insects, male and female, the latter full of ova, 

 which, in the course of the same night, were deposited on the sides of the glass, 

 in a cluster, to the number of seventy-nine. In order to give the insects food, I 

 tried the experiment of their feeding for a time on the dead gold-fish, which they 

 did for two days ; when, on their appearing rather weakly, I removed them from 

 the fish, and the water becoming impure, I restored them to the glass where the 

 eggs were deposited ; they became evidently refreshed, and the female hovered 

 over and about the spot where the previous eggs were laid, and in the course of 

 the same night she laid twenty-four more, and, after a short time died. By way 

 of experiment, and as a resource for food, I had some minnows caught for the 

 other, to see if it would feed upon them. It remained in the vessel for two days, 

 when it disappeared, and I suppose it was eaten by the minnows. The eggs still 

 remain unhatched, June 13th." 



The engraving at the commencement of the article represents the Argulus fo- 

 liaceus magnified, and of the natural size. 



