CHIROCEPHALUS. 47 



organ appears to be double or bifid, cylindrical, transparent, 

 and, according to Schceffer, 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 

 Schoefter 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 Daphnise, 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 



