PACKARD.] . TEANSFOEMATION OF AETEMIA. 493 



schibai Lake hj rain, the furca becomes in the late generations longer 

 and the number of bristles greater, since under these conditions the 

 growth of Artemia salina is less retained and the sexual maturity ap- 

 pears not so early, that is, not earlier than the complete development 

 of the body-parts, which, however, is not so well defined in this species, 

 being, as it were, but a relative matter. Also the termination of the 

 upper auteunfe, being the most constant character of this species, modi- 

 fies to a certain degree. For instance, I found in the autumn of one 

 year, at low temperature and diluted salt water of the Chadschibai 

 Lake, in many individuals of A. salina near the end of the upper an- 

 t-ennee five olfactory bristles, instead of the normal number of four. In 

 domesticated generations of this species in-gradually diluted salt water 

 we perceive also five olfactory bristles on the upper antennae. With 

 the distinctive characters of A. salina we have also to include the form 

 of the gill-sacs. They are in A. salina of an elongate form, their width 

 being on the average twice less than their length. This character dis- 

 tinguishes A. salina from A. mllhausenii, in which the gill-sacs are of 

 oval or more rounded form, being on the average two-thirds as wide as 

 long. 



As another important point of distinction of A. salina from the nearest 

 allied races, I mention the proportional size of the posterior part of the 

 body constituting the apodous segments; the anterior part from the 

 beginning of the head to the end of the last leg-bearing segment, i. e., 

 to the beginning of the first apodous segment and the posterior part of 

 the body, from the beginning of the first apodous segment to the end 

 of the last segment before the beginning of the furca. The furca does 

 not come into account, as its length is variable, being for instance in 

 A. milhaiiscnii, with which the other forms must relatively also be com- 

 pared, entirely missing. We find that in A. salina the anterior part of 

 the body is somewhat shorter than the posterior; proportionate to it 

 as five to six or as five to seven. This relation of the parts also depends 

 upon the concentration of the salt water in which these generations 

 live. In reduced concentration the posterior part has an inferior size 

 than in the higher concentration. Altogether the postabdomen of A. 

 salina becomes longer and more slender with increased concentration. 

 In many of our specimens with the character of A. milhatisenii, which live 

 at self-deposition of salt or nearly so, the anterior part of the body is 

 twice shorter then the posterior part. 



To the most variable characters of A. salina we must reckon that 

 reddish layer which lines the anterior part of the alimentary canal in 

 the shape of a tube, which layer Joly^ calls the liver, and Ley dig ^ the 

 stomach, as he separates it from the following part, the alimentary canal 

 to the anal orifice. For better distinction I shall call the anterior part 

 the stomach i)art of the tract, the second, the posterior part? The 

 stomach part of the tract terminates in Artemia about in the middle of 

 the seventh apodous segment, but the length of this part depends upon 

 the concentration of the salt water inhabited by the generations of this 

 species, and i>artly also from the growth (age) of the specimens. At 

 high salt capacity of the water this part of the tract does not reach to 

 the end of the sixth apodous segment of the abdomen; at lower salt 



' "Snr 1' Artemia salina" in Annales des Sciences nat. 1840, pp. 238 to 239. 



2 F. Ley dig, "Ueber Artemia salina und Brancliipus stagnalis," Zeitschriffc f. -v^-. Z. 

 1851, pp. 283 to 2154. 



3 The first part of the tract Clans calls "Magendarm," the second part, the "End- 

 Dann" in his "Znr Kenntniss des Banes und der Entwicklung von Branchipua stag- 

 nalis und Apus cancriformis," 1. c, as above. 



