CHIROCEPHALUS. 
47 
organ appears to be double or bifid, cylindrical, transparent, 
and, according to Schoeffer, composed of two joints. The 
oviferous sac, or external ovary of the female, is very large, 
and distinctly visible. It is conical, and the point opens 
like the beak of a bird, to allow the eggs to escape. 
Prevost, however, informs us that the vulva is not situated 
here, but what appears singular, is placed at the extremity 
of the tail on each side of the anus, being double or bifid, 
to correspond with the double penis of the male. 
The heart or dorsal vessel commences near the head, 
and terminates at the end of the penultimate ring of the 
body. It is brilliant, quite diaphanous, and consists of a 
series of small hearts, as Prevost calls them, to the 
number of about eighteen or nineteen, all placed end to 
end, and all moving together. It was pointed out by 
Schceffer in the Branchipus. 
The digestive canal, commencing at the mouth, at first 
mounts up a little, then curves downwards, and runs 
along the body, terminating in the anus, between the 
caudal segments. 
The Chirocephalus is found in stagnant water : very 
often in the ditches and deep cart-ruts on the edges of 
woods and plantations. 
It is rarely to be met with in this country, compared 
with the Daphniae, and many other Entomostraca : the 
only place near London where I have met with it being 
on Blackheath. They swim upon their back, and in fine 
warm weather, when the sun is not too strong, they may 
be seen balancing themselves, as it were, near the surface 
by means of their branchial feet, which are in constant 
motion. On the least disturbance, however, they strike 
the water rapidly with their tail from right to left, and 
dart away like a fish, and hasten to conceal themselves 
by diving into the soft mud, or amongst the weeds at the 
bottom of the pool. They are nearly transparent, and 
are of a very light reddish colour, with a slight tinge of 
blue on some parts. “ When placed in a glass of clear 
water,” says Prevost, “ the elegance of its form, the ease 
