A. E. Verriil on new American Phyllopod Crustacea. 247 
from the tubs, when examined with a high power of the micro- 
scope, was found to be filled with immense numbers of infusoria 
of various kinds, such as monads, vibrios, and bacteria, most 
of which were so small as to be distinguishable only as moving 
points with a } inch objective. 
| In the salterns of France the Artemie are associated with 
immense numbers of a monad, usually bright red in color, 
_ -which has been named Monas Dunalii by Joly, who attributes 
to it the red color which the brine assumes just before crysial- 
__ lization,* as well as the red color observed in the Artemia, 
_ which doubtless feed upon it, as well as upon various other 
____ living infusoria, and dead animal and vegetable matter of vari- 
ous kinds.t The Monas Dunalii appears in abundance in the 
water having the density most favorable for Artemia, but in- 
creases in far greater proportion in the still denser, nearly or 
quite saturated brine in which Artemia does not live. The 
observations of Payen and Joly show that the A. salina of 
_ #rance can exist in waters varying in density from 4° to 2v° 
_ Baumé, but that they flourish best in those that have a density 
of 10° to 15°. According to Rackett those of Lymington do 
not live in the water which is undergoing the first stage of con- 
centration, but only in the pans of concentrated brine, contain- 
ing about “a quarter of a pound of salt to the pint.” 
Our A. gracilis can exist without apparent inconvenience 
when the water in which they occur is diluted with an equal 
bulk of fresh water as well as when it is much concentrated 
by evaporation. The water in which they were found varies in 
density from 1-060 to 1-065. 
* Reserches sur la Coloration en rouge des Marais Salans Méditerranéens, par 
M. Joly, Annals des Sciences naturelles, 2¢ ser., t. 13, 1840, p. 266. 
._ + According to M. Joly, op. cit. p. 262, a beetle, Hydroporus salinus Joly, also 
inhabits the salterns, where the water has a density of 6° or 7° Baumé, and 
Preys upon the Artemie. ‘ : 
t 4° to 20° Baumé is equivalent to a density of about 1:02 to 1°16; 10° to 15 
=1075 to 1-117. A brine having a density of 1-020, which is nearly that of sea- 
Water, contains about 2°766 per cent of salt; one of 1-160 contains 21'219 per 
Sent; one of 1-075 about 10-279 per cent; 1-117 about 15°794 per cent. 
* 
