. The crustacea of the plankton, July, 1894-Dec., 1896 . 241 337 ? 6 8 114 101 33 * IV. 80136 3311 VI. 74127 40 VII. 83145 650 * No nauplii included. The number of Cyclops when at its maximum showed sur-prisingly little variation. In 1895 from May 1st to June 6th,26 catches were made on 13 days. The catch ranged from10,000 to 20,000 individuals actually caught. In 1896, 18 catcheswere made on 16 days. The numbers ranged from 9,000 to 37, figure is added (Fig. 21) showing the number of Cyclops
. The crustacea of the plankton, July, 1894-Dec., 1896 . 241 337 ? 6 8 114 101 33 * IV. 80136 3311 VI. 74127 40 VII. 83145 650 * No nauplii included. The number of Cyclops when at its maximum showed sur-prisingly little variation. In 1895 from May 1st to June 6th,26 catches were made on 13 days. The catch ranged from10,000 to 20,000 individuals actually caught. In 1896, 18 catcheswere made on 16 days. The numbers ranged from 9,000 to 37, figure is added (Fig. 21) showing the number of Cyclopscaught during the year 1895. It will be seen that the diagramgives no warranty to the conclusion that this species appearsin swarms. Similar illustrations could be taken from any year,and from almost any species, with the qualification that the rangein number is greater in the case of those species whose num-bers are small. Trans. Wis1, Acad., Vol. XL Plate XXXL 800. 700. 600. 500. 400. 300. 200. 100. ...1,200 ...1,100 J*ay ...1,000 • I 1. Fig. Jan. Feb. Mch. Ape. Mat. June. July. Aug. Sept. Oct. Nov. Dec. 21.—Cyclops. Number of each catch, 1895. The curve indicates the aver-age. Scale, 1 vertical space = 100,000 Crustacea per sq. m. See p. 370. Horizontal Distribution—Swarms. 371 The following table gives the variations of the total numberof the Crustacea during three months of 1896. It will be seenthe variations are somewhat smaller than are those of the singlespecies but are of a similar character, and also resemble thoseof Table XXVI. Table XXVII.—Total Crustacea, May — July, 1896. No. obser-vations. May 16-30July 1-15 .July 16-31 Average. Maximum. Minimum. 2,398 2,966 1,615 1,901 2,963 1,177 845 1,977 561 1,265 1,908 890 1,314 2,332 1,005 795 1,266 511 9 9 6 11 I think that I have given here and in the tables of the ap-pendix, sufficient evidence to enable the student to undertandsthe extent of the variation in the distr
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