274 THE EFFECT OF MOISTURE 



ber of spines on the swimming feet, but none of these 

 differences seem to be especially connected with the de- 

 gree of salinity." Probably the Artemia recently 

 found by R. T. Giinther * inhabiting Lake Urmi in 

 Persia in such enormous numbers is only another local 

 variety of A. salina. It differs from this species in 

 possessing an incompletely segmented abdomen, in the 

 claspers of the male being larger, and in other char- 

 acters, but Giinther says he is nevertheless inclined to 

 agree with Packard that there is only one well-defined 

 Old World species of Artemia, viz., A. salina. 



Schmankewitsch also changed the salinity in the re- 

 verse direction, and gradually diluted the salt water 

 containing some A. salina till it finally became per- 

 fectly fresh. The Crustaceans, which had gone 

 through several generations during the process, had 

 meanwhile so changed their character that in Schman- 

 kewitsch's opinion they now resembled the form of the 

 genus Branchipus. Thus the last segment of the post- 

 abdomen became divided into two segments, and 

 Schmankewitsch maintained that this division of the 

 segment is the only structural character really differ- 

 entiating the genus Branchipus from Artemia. How- 

 ever, Glaus f has shown that there are many other points 

 of difference, and that the division in question is not a 

 structural character of great importance. Also 

 Branchipus is distinguished by the sexual characters of 

 its males, which possess no structure in any way similar 

 to the great leaf-like second antennae shown by the 

 male Artemia. "We must conclude, therefore, that 



* Journ. Linn. Soc. (Zool.), xxvii. p. 395. 

 f Auz. Ak. Wiss. Wien., p. 43, 1886. 



