PACKARD.] TKANSFOEMATION OF ARTEMIA. 497 



toward the tip, with sides and ends bristled, whose number fluctuates 

 on each lobe between 12 and 22. The fnrcal lobes are in length only- 

 two and a half times shorter than the last abdominal segment. 



This last (eighth apodons) prolonged segment of the abdomen differs 

 here in the important peculiarity that it jjossesses, a little abovx its 

 middle, often a more or less distinct transverse ring, like an articula- 

 tion, as existing between the eighth and ninth apodous segments of the 

 abdomen in the species of Branchipus, in which the furcal lobes are in 

 the majority strongly developed, as it were, on account of the ninth apo- 

 dous segment, which is rather short with them. This transverse ring 

 is just below the last sensitive bristles, occurring in A. salina a little 

 above the middle of the eighth apodous segment of the abdomen,^ as 

 also at the end of each of the anterior apodous segments just before the 

 segmentations. If this transverse ring on the eighth prolonged apo- 

 dous segment was more conspicuous in variety h. of A. salina, and if it 

 was of constant occurrence, then we would have a form with nine 

 apodous abdominal segments, which is one of the principal characters 

 of the genus Branchii^us. But since there is no actual segmentation 

 on the eighth apodous abdominal segment of variety h. of A. salina., this 

 race forms, remaining with the genus Artemia, a transitory linlc be- 

 tween this genus and the genus Branchipus. With the latter genus 

 the examined race i30ssesses by far more harmony than the other hith- 

 erto known forms of Artemiae. The prolonged, laterally and terminally, 

 bristled furcal lobes, the transverse ring between these lobes and the 

 abdominal end, the shortness of the postabdomen, the lesser length in 

 proportion to these parts in other Artemia forms, the greater thickness 

 of the segments of the postabdomen, the more or less distinct traces of 

 segmentation on the last (eighth) apodous, homologous with the two 

 last (eighth and ninth apodous) segments of Branchipus, likewise also 

 yet other less conspicuous characters of Artemia salina varietas b., 

 demonstrate this. 



Amongst the characters in which the examined Artemia-form incline 

 to the genus Branchipus I will note two more. One of them consists in 

 the presence of groups of spines on the ventral and lateral surface of the 

 postabdomen, on the end of the third, fourth, fifth, sixth, and seventh 

 apodous segments, anteriorly of each segmentation, and a little before 

 the middle of the eighth apodous segment before the more or less notice- 

 able transverse ring on this segment. On some segments occur two 

 aggregations, one on each side, but on others occur lour aggregations 

 arranged circularly around the segment. From the middle of each ag- 

 gregation arises a sensory bristle, which, together with the groups of 

 spines situated near their base, can easily be seen under a magnifying 

 power of 350. In A. salina and its variety a. occur, instead of groups of 

 spines, on the same spot groups of cuticular cells, which do not rise 

 above the surface of the integument (from which they are somewhat 

 differentiated), and which give rise to one bristle arising from their midst. 

 These comi^lexes of cuticular cells in A. salina and in its variety a. are 

 homologous with the mentioned complexes of si)ines in race h. of A. salina 

 and the species of Branchipus. In domesticating several successive 

 generations of the species A. salina in gradually diluted salt water, I 

 obtained, together with the other corresponding characters on the post- 



^On this spot of the last segment of the ahdomen we obtain the segmentation in the 

 species A. salina by domesticating several of its generations in gradanally diluted salt 

 water. Compare my paper in the "Schriften" of the third meeting of Russian natu- 

 ralists at Kiew, Zoological section, j)p. 71 and 87; also, my pajjcr in Z. f. w. Z., sxv, 

 1871. 



32 H 



