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. 
