NOTOMBEE 9, 1906.] 



SCIENCE. 



595 



individuals under different environmental con- 

 ditions (primarily the varying density or salt 

 concentration of the waters in which the crea- 

 tures live). In 1898 Anikin determined, to 

 his own satisfaction at least, that the struc- 

 tural changes induced in Artemia individuals 

 of succeeding generations by rearing these 

 generations in salt water of differing density 

 were not true species differences, fixed and 

 heritable, but simply ontogenetic differences 

 maintained only as long as the particular 

 inducing influences (denser or less dense salt 

 water) persisted. Certain specific characters, 

 particularly those of the male, did not change 

 at all, so that Anikin believed himself to be 

 able still to recognize his original species 

 throughout all the generations grown under 

 modified conditions, although the species was 

 actually plainly modified in structure in cer- 

 tain particulars. These structural changes, 

 however, he found could be avoided if the 

 changes in environment were made very grad- 

 ually. When made violently the changes were 

 marked, and could perhaps be interpreted to 

 be those of degenerative or arrestative modi- 

 fication. In other words, the rearing of young 

 in a salt water of higher concentration than 

 that normal to the species worked injury or 

 arrestation in the development. These modi- 

 fications as noted by both Schmankewitsch 

 and Anikin were chiefly concerned with the 

 segmenting of the abdomen and the length 

 and hairiness of the caudal appendages. As 

 differences in exactly these characters were 

 those by which the European species of 

 Artemia (and partly the genus Branchipus) 

 were distinguished, it is not surprising that 

 Schmankewitsch believed himself to see Ar- 

 temia salina transform into A. milhausenii, 

 and vice versa; and even the genus Artemia 

 change to the genus Branchipus. However, 

 the correct interpretation of the affair is, prob- 

 ably, that the original describers of the Euro- 

 pean species had before them various ' onto- 

 genetic species ' of Artemia, i. e., nutritional 

 or developmental varieties. 



In America three species of Artemia have 

 been recognized; one A. gracilis Verrill, from 

 barrels or casks of salt marsh water exposed 



(and hence much denser than the original 

 marsh water) on a railroad bridge near New 

 Haven, Conn.; another, A. fertilis Verrill, 

 from Great Salt Lake, and the third, A. monica 

 Verrill, from Mono Lake, Cal., a strongly salt 

 and alkaline lake in the Owens River desert. 

 All of these Artemias are living in salt water 

 of a density much greater than that of ordi- 

 nary sea water. The water in the New 

 Haven casks varied in density from 1.06 to 

 1.065; the water in Great Salt Lake has a 

 density of 1.17 and that in Mono Lake is 

 certainly not less dense and is " so alkaline 

 that it is said to be used for removing grease 

 from clothing. It is said to contain, also, 

 biborate of soda." I know of no experiments 

 with the American Artemias except that Ver- 

 rill states that 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.' 



To the short list of American species I have 

 to add a new one collected by student David 

 Fulloway from the evaporating pools of a salt 

 works at Redwood City (five miles from Stan- 

 ford University) on the west shore of San 

 Francisco Bay. This west coast Artemia 

 differs markedly from the other American spe- 

 cies in those characteristics upon which Ver- 

 rill relies to distinguish the already known 

 American forms, viz., the shape of the male 

 claspers, the female egg-sac, and the character 

 of the caudal appendages. The character of 

 size upon which Verrill seems to have placed 

 some reliance is a frail support, for it gives 

 way when individuals reared under different 

 conditions (density of salt water) are com- 

 pared. The new species may be named and 

 described as follows: 



Fig. 1. Posterior tip of abdomen, showing 

 caudal appendages of male Artemia franciscana, 

 n. sp. 



