PACKARD.! TRANSFORMATION OF ARTEMIA. 495- 



tho mean length of Artemia salina var. a. As a rule the specimens of 

 this variety are two lines or nearly so larger than the specimens of the 

 species.^ 



With the mean size as a point of distinction, the fact may serve to 

 show that the posterior part of the body in this variety from the begin- 

 ning of the first apodous segment to the end is somewhat longer than 

 in the normal species. The anterior part of the body in Artemia salvia 

 is in x)roportion to the posterior part in most cases as 5 to 6 (or 5 to 7 

 in higher concentration of the water), but in this variety usually as 5 

 to 8, slightly fluctuating to this or that side in different salt capacity of 

 the water. The postabdomen in this variety is not only longer, but 

 also slenderer than in the normal species. 



The furca is longer in the variety than in the species, and the number 

 of bristles on the furca is also greater in the variety. If the furca in the 

 species is six times shorter than the last prolonged segment of the ab- 

 domen, then it is but four times shorter than that segment in the race. 

 But we also meet with specimens of the species with such a proportion 

 of the furca to the last segment, as in this variety, and again we see 

 furcal lobes in specimens of the variety with the same proportion to the 

 last segment as in the normal species. In Artemia salina, occur from 4 

 to 12 bristles on each lobe of the furca, rarely more ; in the variety a. 

 of Artemia salina there are from 8 to 15, but seldom more. In this 

 race, as well as in the species, we find however also less than four 

 bristles on each furcal lobe ; there occur three, two, and one bristle on 

 each lobe, especially in more concentrated water; but such sp<^cimens 

 and generations must, by modifications of other structures, be regarded 

 as transitory forms between Art salina and A. millbausenii. 



The claspers or second antennae of the males of the variety are less 

 hroad than in the males of the normal species. The grouiJs of spines or 

 teeth on the anterior part of the claspers, near their base, are some- 

 what better developed in the males of the variety than in the males of 

 the species A. salina. The second antennae of the females of this race 

 are a little smaller and narrower than in the normal species, just as the 

 male claspers are narrower than in the species. 



The specimens of the variety a. of Artemia salina are of a far darker 

 red color than the specimens of the species, although there occur also 

 specimens with the same color amongst the latter. The variety a. of 

 A. salina is usuallj^ of a red color, and is found here in the Kujalnitzki 

 salt lake, but Art. salina is usually of a grayish or reddish-gray color, 

 occurring principally in the Ohadschibai salt lake, in Avhich occur also 

 specimens of red color,^ which represent, as it were, the points of aber- 

 ration of the species toward its race (var. «.). 



In the variety a. of Artemia salina the gill- sacs are a little smaller; 

 the posterior branchial lobes, on the other hand, a little larger than in 

 the normal species. According to the other structures, it does not 

 differ from the species Artemia salina; and all that was said relative to 

 the influence of the surrounding element about the species refers also 

 to the variety a. of A. salina. 



All the characters of this variety correspond with the circumstance 

 that specimens of them, in comparison with the specimens of the spe- 

 cies, prosper better at a higher concentration of salt water, but at a 

 lower temperature. 



' The specimens of the species are about 14""^ length, the specimens of this variety 

 17 or 18™™. The summer generations are in one, as well as in the other for)n, a little 

 smaller than the fall generations. 



■2 The Kujalnitzki Lake has more saline water than the Ohadschibai Lake. 



