FACKARD.J TRANSFOEMATION OF ARTEMIA. 513 



This location corresponds to that, where in Artemia on the long segment an 

 articulation is formed, if we domesticate entire generations in gradually- 

 diluted salt water (esi3ecially at not too high temperature), and also to 

 that location where in the BrancJiipidce this articulation exists between 

 the eighth and ninth apodous segment. It would look too forced, on 

 account of a single character, to include the one assemblage in the genus 

 Artemia, the other in the genus Branchipus. By this rather unnatural 

 systematic treatment Branchipus stagnalis would come into the genus 

 Artemia, though this species according to its characters, with the excep- 

 tion of the eighth apodous segment, belongs to the genus BrancJiipus. 

 I note that in regard to apodous segments Branch, stagnalis has not the 

 full characters of Artemia, as with it the last (eighth) apodous segment 

 is not so long as compared with the preceding, as in Artemia. There 

 are other structures, according to which the species of Branchipus can 

 be distinguished from Artemia. Such a character is that in the males 

 of Artemia the claspers toward the end, that is, in the second half (last 

 joint) become broader, so that the second half is tabulate, which does 

 not occur in Branchipus, since their male claspers are not tabulate 5 

 moreover, their first half is broader and thicker than the second.^ 



The circumstance that there are often certain appendages on the clasp- 

 ers or on the front of various Branchipidce, and that the furca generally is 

 tabulate and better developed, can be but partly regarded as a character 

 of Branchipus. On the male claspers of Artemia, we see also certain 

 appendages in the shape of little tuberoi^ties for holding the female; 

 we even see whole groups of denticular spines, while in certain species 

 of Branchipus {Branchipus ferox Grb. and B. medius mihi) no append- 

 ages at all occur on the claspers of the males. Although the branches 

 of the furca in Artemia have mostly the shape of a stylet, or are conical 

 in shape, there are, nevertheless, also Artemice with tabuliform branches 

 of the abdominal furca, like the second variety of Artemia salina (var. 

 b.), Artemia salina itself has even often a large development of the 

 furca under the influence of certain external conditions. Otherwise, 

 the furca of the above-mentioned Branchipus medius resembles this 

 part in Artemia, only it is somewhat obliquely cut off or shoe-sole-shaped, 

 curved.^ Concerning the statement that the furca in Artemia was only 

 terminally bristled, this is incorrect, as even in one and the same species 

 the furca can be more or less developed, being bristled either terminally, 

 or both terminally and laterally, according to conditions in life. Bu5 

 there is a physiological feature, which can be added to the charac- 

 ters distinguishing the species of Artemia from those of Branchipus ; in 

 the genus Artemia the phenomenon parthenogenesis is known to occur, 

 which is unknown with Branchipus. After all this is a negative char- 

 acter for Branchipus, but is important together with other structures 

 in Artemia. Consequently, according to my view, the distinguishing 

 characters of the genera Artemia and Branchipus are the following : 



Genus Artemia. 



Eight apodous abdominal segments, of which the first two bear the exter- 

 nal sexual organs, but the last about twice as long as the preceding, being 

 homologous to the last two abdominal segments, the apodous eighth and 

 ninth, in Branchipus. The segments of the abdomen have a considerable 



' In some species of Branchipus, like B. ruiricaudatus Klunzinger, the male claspers 

 are divided at the end into several branches. 



2 Consult my paper in the "Schriften" of the third meeting of Russ. Naturalists at 

 Kiow, 1871, Zoological section, Plate III, figs. 1 to 3 and 5. 



33 H 



