510 GEOLOGICAL SURVEY OF THE TERRITORIES. 



from Artemia a i>roper group or a subgenus of the genus Brancliipus, 

 like Brancbipus proper and Poly artemia. Dr. Grube, nevertheless, 

 gave iu reference to the then known facts of Artemia a mistaken char- 

 acteristic of his subgenus Artemia^ saying, amongst other things, that it 

 possessed six apodous segments and that the short furca was only 

 bristled at the ends (})ppendicibus caudalibus brevibus, apice tantum 

 setosis ....). Eelativetothenumberof apodous segments of the abdo- 

 men, Grube repeated the statement of those authors (Joly) who in Ar- 

 temia did not take into consideration the first two apodons segments of 

 the abdomen, bearing the external sexual parts. Without these two 

 first apodous segments of the abdomen Artemia has really six apodous 

 abdominal segments, but since the external sexual organs answer mor- 

 phologically to modified limbs, we only in this sense can count in Ar- 

 temia six segments of the abdomen; like Branchipus in this case it 

 would have but seven and not nine segments. But Grube in this sense 

 does not count six apodous segments iu Artemia, as he demonstrates 

 nine apodous segments for his subgenus Branchipus, and we can see 

 from the general diagnosis of the genus Branchipus (1. c, p. 136), that 

 those segments, bearing the external genitals, were taken in with the 

 apodous segments of the abdomen of Ms genus BrancMinis^ i. e,, inclu- 

 sive of Artemia and Polyartemia. But, in fact (as mentioned above in 

 the completed description of Artemia salina) the species of Artemia, have 

 eight apodous abdominal segments, the first two of which bearing the 

 external genitals, and of which the last is nearly twice as long as the 

 preceding and is homologous with the two last apodous segments of the 

 species BrancJiipus, but the BrancMpodcc have nine apodous abdominal 

 segments, of which the first two also bear the genitals, and of which the 

 last, located before the furca, is not longer, but usually shorter than the 

 preceding. ^ 



In regard to the position of the furcal bristles in Artemia3 I have 

 already stated above that in our forms of Artemia the bristles are not 

 only at the end but also often on the margins of the furca, and that 

 these bristles often occur also in great numbers, the furca assuming, as 

 in variety h. of Artemia salina,, a plate form. 



If we ask now whether all species of Branchipus really possess nine 

 apodous segments, of which the two last ones are homologous with 

 the prolonged last segment of Artemia, then it seems indeed to be the 

 case. Only Branchipus sfagnaUs could form an exception. At least 

 from the statements of the authors ^ the number of apodous abdominal 

 segments (whether eight or nine) cannot be inferred with certainty, and 

 I myself had not hitherto occasion to examine Branchipus stagnalis. 



Concerning the question whether all the species of the genus Artemia 

 have eight apodous abdominal segments, and whether in all the last 

 segment is j)roionged and homologous with the last two abdominal 



' In my paper in Zeitschrift f. w. ZooL, vol. xxv, supplement part, appearing under 

 the title " Ueber das Verhiiltniss der Artemia salina M. Edw. zn Art. milhausenii M. 

 Edw. nnd dem genn.s Brancbipus," I must add a correction relative to the propor- 

 tional length of the last abdominal segments in Branchipus. Thei'e it says : "Branchi- 

 pus has nine last apodous segments, of which the two neighboring segments show 

 oiilj^ a small diiferencein length among themselves" (1. cit., pp. 106 and 110). loughc 

 to have said: "Branchipus has nine apodous abdominal segments, of which the last, 

 situated before the furca, is not longer but usually shorter than the preceding seg- 

 ment." 



^Leidig, "Ueber Art. salina und Branch. sta,gnalis." Zeit. fur w. Zool. 1851, p. 

 231. Spangenberg, " Zur Kenntniss von Branch, stagnalis" in Zeit. f. wiss. Zool. 

 187(i. pp. 8 to 9. Supplement part. Clans, "Zur Kenntniss des Banes und der Ent- 

 wickluug von Branch, stagnalis und Ai)us caucrif." Goettingeu, 1873, j). 14, Tab. V, 

 ih' 10. 



