106 Dr. SuAw's Defcription of the 
In March and April the females depofit their eggs, without any 
fettled order, and perfectly loofe in the water. They appear to the 
naked eye like very minute globules of a light brown colour; fcarce, 
if at all, exceeding in fize the particles of the farina in a mallow: and 
what makes this comparifon the more juft, is, that each ovum, when 
magnified, is extremely like one of the globules of farina in that 
plant; for it is thickly befet on every fide with fharp fpines, 
the length of which is equal to about the fourth part of the dia- 
meter of the egg. Befides thefe fpines, the egg is coated over with 
a tranfparent fubftance, reaching juft to-the extremities of the 
{pines. 
This is a particularity of ftruéture which I do not remember to 
have obferved in the ovum of any other infeét; and may probably 
be intended to affift in caufing them to adhere to the fubftances on 
which they fall when depofited in the water, or elfe as a fecurity 
from the fmaller water-infects. | 
In the fpace of a fortnight, or in cold weather rather more, they 
are hatched; and the young animals may be feen to {wim with great 
livelinefs by means of three very long pairs of arms, or rowers, which 
appear difproportioned to the fize of thé animal: and indeed it bears, 
in this very fmall ftate, not much refemblance to the form which it 
afterwards affumes; but, in the fhort fpace of a very few hours, the 
body appears confiderably lengthened, and it begins to acquire the 
remarkable character of the divided tail-fin, which fo ftrikingly dif- 
tinguifhes the parent animal. In this very young ftate the eyes do 
not appear pedunculated, but like a dark fpot on the middle of the 
head. 
On the feventh day after hatching, they approach pretty nearly to 
the form of the complete animal, except that they ftill retain the 
two firft or long pairs of rowers or arms: the legs however, or fins, are 
atthis period very vifible. After this time it lofes the long rowers, 
4 and 
