Cancer flagnalis of Linnaus. - 140g 
and appears ftill more like the infect in its advanced ftate. Its 
growth, however, is but flow; and in all probability a very confide- 
rable time elapfes before the infect acquires its full fize: but this I 
cannot prefume to determine, fince thofe which were hatched in the 
glaffes in which I kept them, died before they had acquired any con- 
fiderable fize. 
In order to obtain thefe infe&s in a young ftate, nothing more is 
required than to keep the females felected for this purpofe in fepa- 
rate glaffes of the fame water in which they naturally refided. 'The 
glaffes fhould be fmall; and, when the eggs are depofited, the parent 
infects muft be removed, and the glafles kept in a temperate room. 
When firft hatched, they are very little fuperior in fize to a com- 
mon mite. | 
The three microfcopic views of the young animals were drawn 
with the greateft attention, and their accuracy may Le fafely 
depended upon. 
TAB. 9. Fig. 1. Shews the young infect very foon after haniais 
Fig. 2. Reprefents it fome hours after, at which time thé for king 
of the tail is juft vifible, as well as the fegments of the body; whereas, 
in fig. 1, the body has not yet lengthened itfelf fufficiently to fhew 
the joints of which it confifts, or the forking of the tail. 
Fig. 3. Shews it on the feventh day after hatching. 
It is remarkable that the Cancer ftagnalis, in its complete ftate, 
though of the moft delicate ftruéture, is yet capable of fupporting 
a very confiderable degree of cold, as is evident from the animal ma- 
king its appearance in the middle of the day in very fhallow waters, 
which have been almoft entirely frozen during the night. Yet 
Scheffer reprefents thofe which he found to be exceedingly impa- 
tient of cold; and adds that he has known a whole race of them 
completely killed in their native water by a very flight froft. This 
is certainly not the cafe in our own country. I have feen great num- 
Es * bers 
