492 GEOLOGICAL SURVEY OF THE TERRITORIES. 
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 descriptions of specimens gathered 
under various physical conditions, that is, at various concentrations in 
‘combination with temperature. Milne-Edwards! says: That on each 
furcal lobe in Artenvia salina occur three or four bristles, while Grube? 
states, in his diagnosis, that 5 to 8 bristles occur on each furcal lobe. 
We find in Artemia salina from our district, under various 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 furea. I take the latter form to be another variety or 
race of Artemia 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, popa- 
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 fureal 
lobes. The specimens of Artemia from the very saline Kujalnitzki Lake, 
having but three, two, one bristles on the end of the furcal lobes, or 
lacking them altogether, in the latter case having a very slightly de- 
veloped furea, with the other parts moditied ; those I take to be tran- 
sitory forms between 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 Artemiz. 
In Artemia salina, as one of the most constant points of distinction, 
we observe the termination of the superior antenné or antenne of the 
first pair. The upper antenna here terminates with two protuberances 
or papille 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 tle 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 upper 
surface, arise three moderately long and usually curved bristles. 
Beside the mentioned terminations of the upper antenne we have to 
complete the description of Artemia salina by the following characters. 
In Artemia the posterior part of the body 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 preceding, 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 furea is on the average six times shorter than the prolonged 
last abdominal segment. . The bristles of the furea are also of very 
variable number. We notice in our Artemia salina on each lobe of the 
fureca 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 des crustacées, Vol. III, p. 370. 
2¢¢ Bemerkunken tiber die Phyllopoden,” Arch. f. Nat. 1853, p. 144. 
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