LEKNEADiE. 
819 
from one place to another, how is it that we thus find 
them fixed upon these fishes, mature and possessing ova? 
Blainville answers this question, by saying, “it is difficult 
to conceive how these animals, which spring from eggs, 
are fixed upon fishes without admitting that in their young 
age they possess a little motion/’ M. Surriray had at 
that time demonstrated to Blainville the existence of the 
young when just hatched ; but less importance was at- 
tached to this discovery than it deserved ; and it was not 
till Nordmann corroborated the fact, and followed it up 
by his more patient researches, that we were enabled to 
answer the question fully. 
The circumstance that the Lerneadse soon die after being 
taken from the fish that has served them for nourishment 
and a habitation, certainly throws great difficulty in our 
way of observing the development of the young ; but we 
now know that when hatched, and for some time after- 
wards, the young Lerneadm are nimble and active, and 
possess both the organs of motion and the faculty of 
using them. When they first come out of the egg they 
are of an oval shape, and very much resemble the young 
of the Cyclopidae. They possess a large eye, situated in 
the centre of the anterior and upper part of the body, and 
are provided with two large pairs of swimming-feet, and 
a pair of jointed antennae. As in the Cyclopidse, these 
young Lerneadse cast their skin repeatedly before they 
arrive at maturity. After the first moulting, the body is 
seen plainly divided into two parts, the anterior of which 
is furnished with three pairs of hooked feet, and the pos- 
terior with two pairs of swimming-feet. No doubt there 
are a good many stages of development to go through 
before they assume the mature form, but it has not yet 
been possible to follow them out. It is not the least 
curious part of the history of these singular-looking ani- 
mals, that the young should thus stand on a higher stage 
of development than the mother ! and that their progress 
from youth to maturity should be in the directly opposite 
ratio to that of all the other Crustacea. At what period 
