492 GEOLOGICAL SUKVET OF THE TEREITOEIES. 



furca, the furca being at the same time shorter and less bristled, as un- 

 der opposite physical conditions. If we compare the descriptions and 

 illustrations of Artemia salina of the various authors, we find that they 

 agree less among themselves than they do compiled from specimens of 

 Artemia salina^ or taken from the descrixitions of specimens gathered 

 under various physical conditions, that is, at various concentrations in 

 combination with temi)erature. Milne-Edwards^ says: That on each 

 furcal lobe in Artemia salina occur three or four bristles, while Grube^ 

 Btates, in his diagnosis, that 5 to 8 bristles occur on each farcal lobe. 

 We find in Artemia salina from our district, under vatious behavior of 

 the surroundings, on each lobe of the furca 4 to 12 bristles, seldom more. 

 In the third form, living in salt ditches in the neighborhood of Odessa 

 and the Krimea, we find 12 to 22 bristles on each lobe of the pretty- 

 well developed furca. I take the latter form to be another variety or 

 race of Artetnia salina, though it obviously originated from generations 

 of this species with progressive development under the influence of salt- 

 water ditches, having a lower saline capacity than the salt lakes, popu- 

 lated with Artemia salina. In those cases, where in our Artemia are 

 more than five or six bristles on each lobe of the furca, the bristles are 

 distributed not only near the end but also on the sides of the furcal 

 lobes. The specimens of Artemia from the very saline Kujalnitzki Lake, 

 having but three, two, one btistles on the end of the furcal lobes, or 

 lacking them altogether, in the latter case having a very slightly de- 

 veloped furca, with the other parts modified ; those I take to be tran- 

 sitory forms hetween Art. milhausenii and Art. salina; altogether the 

 distribution of bristles on the furca, the number of bristles, and the 

 shortness of the furca itself can not serve as an important distinctive 

 character between the genera Artemia and Branchipus, and much less 

 so as a point of distinction between the species of Artemi^e. 



In Artemia salina, as one of the most constant points of distinction, 

 we observe the termination of the superior antennae or autennce of the 

 first pair. The upper antenna here terminates with two protuberances 

 or ijapillse of the form of a truncated cone, one of which is somewhat 

 stouter than the other. At the terminus of the stouter, broader cone, 

 we notice three moderately short spines, only one of which can be seen 

 on the terminus of the thinner cone. Each spine is a li tie curved, 

 having at its base a quadrate, yellowish, light-refracting body. These 

 four spines are the olfactory bristles of these animals. Immediately 

 under the terminus of the upper antenna, near the end of its ui^per 

 surface, arise three moderately long and usually curved bristles. 



Beside the mentioned terminations of the upi^er antennae we have to 

 complete the description of Artemia salina by the following characters. 

 In Artemia the posterior part of the bodj" consists of eight apodous seg- 

 ments, the first two of which bear the external genital organs, but 

 the last eighth segment is twice as long as the ])receding, being homo- 

 logous to the two last apodous segments of the Branchipodes. The 

 furca in Artemia salina is of very variable length. In our Odessa A. 

 salina the furca is on the average six times shorter than the prolonged 

 last abdominal segment. The bristles of the furca are also of very 

 variable number. We notice in our Artemia salina on each lobe of the 

 furca from four to twelve bristles, which are not only near the end of 

 the lobes, but for the greater part distributed along their sides, at least 

 if there are more than four or six bristles on each lobe. Toward autumn 

 at a lowering of temperature and dilution of the salt water of the Chad- 



1 Histoire naturelle ties crnstac^es, Vol. Ill, p. 370. 



»" Bemerkunken iiber die PhyUopodeu," Arch. f. Nat. 1853, p. 144. 



