58 BRITISH ENTOMOSTRACA. 



opening at its lower extremity to allow the ova to escape. 

 The digestive tube commences a little above the man- 

 dibles, and is preceded by a pharynx, consisting of two 

 vesicles, which appear divided into cells, and present the 

 appearance of convolutions similar to those of the brain of 

 the superior animals. 



The heart or dorsal vessel is exactly like what is seen 

 in the Chirocephalus. 



The Artemise are found exclusively in salt water, and 

 though they do occur in salt marshes, still they are to be 

 found in greatest abundance in water that is very highly 

 charged with salt. " ]\Iyriads of these animalculi," says Mr. 

 Rackett, " are to be found in the salterns at Lymington, 

 in the open tanks or reservoirs where the brine is deposited 

 previous to the boiling. It attains the desired strength 

 by evaporation, from exposure to the sun and air, in about 

 a fortnight. A pint contains about a quarter of a pound 

 of salt, and this concentrated solution instantly destroys 

 most other marine animals." In these reservoirs there is 

 always a certain quantity of this strong brine allowed to 

 remain, and there these little creatures are found in greatest 

 abundance and in greatest enjoyment ; whilst in what are 

 called the sun-pans, where the brine is made by the ad- 

 mission of sea-water during the summer, and which are 

 emptied every fortnight, they are never found at all. 

 During the fine days in summer they may be observed in 

 immense numbers near the smface of the water, and as 

 they are frequently of a lively red colour, the water ap- 

 pears to be tinged with the same hue.* " There is nothing 

 more elegant," says M. Joly, "than the form of this little 

 Crustacean ; nothing more graceful than its movements. 



* The fact tliat salt water, when highly concentrated, freciuently assumes a 

 red colour, has been often attributed to the presence of great numbers of the 

 Arteiiiia saliiia. Indeed the cause of this red colour, which was well known 

 to take place in the salt marshes and reservoirs of salt water at Mont])ellier, 

 was made, some years ago, the subject of very great discussion in France, 

 before the Institute. M. Payen first maintained the cause to be the pre- 

 sence of Artemiae; M. Duval, however, declared that it arose from micro- 

 scopic vegetables, species of Haematococcus and Protococcus. After a keen 



