163 
MONTHLY AND YEARLY AVERAGES OF READINGS OF RIVER GAGE AT 
HAVANA, 1894-1899. 
(Plane of reference, low water of 1873.) 
Year Jan. | Feb. | Mar.|April| May | June| July | Aug.|Sept.| Oct. | Nov.| Dec. Yearly 
lstoy Lee areeg a 3.92] 4.29] 9.24] 7.40] 7-29] 4.63] 2.32] 1.99] 4.43) 2.96 2.97] 3-41] 4.63 
TOQGi dicta 3.30) 3.51] 6.28] 5.41] 3.68] 1.88) 3.17] 2.43] 3-42] 1.93 2.20] 6.16] 3 61 
ifslofehy aera bis 10.24| 8.83] 9.41] 7.28) 6.58] 7.38] 4.55] 7-42] 4.62] 6.04 5.80] 5-48} 6.08 
TSO 7icraciayers s 11.28)11.13/13.89]13-40| 9.41] 5.54) 6.05] 2.29] 2.01 2.01 2.82] 3-22] 6.90 
itsollaagarae 5-08) 5-94|12.99]14.00, 11.55|11.53| 5-70] 3.66] 4.44 4.86) 7.44| 6.59) 8.02 
1899....---| 7-99) 7-02|13-O5]I1. 15 8.02 7.80 4.38 3.20 2.63] 2.99 3.88] 4-74] 6.40 
HIGHEST AND LOWEST WATER, RANGE, AND TOTAL MOVEMENT, BY MONTHS, OF RIVER LEVELS FROM 
GAGE-READINGS AT COPPERAS CREEK, 1894-95, AND AT HAVANA, 1896-1899. 
(Plane of reference, low water of 1873.) 
January February March April May June July 
| 
a B ® = | = = 
Allee Z| 2l¢ fl 2lelolel2leleolel#lel ol giz ]el ol Zl alelelg 
w{S] Ss] So}, os] h) eo) s/s) ale) a) so) me) se) 8] gs] & so) 2 | so) &) o] S] 3) ale 
S| MES o| | Slaelel|Plslale| @|slale! =! Sl a] 6] =] 3] 51S! S| 8] se 
PIB Alea ae) A ela Alea BAMA BAe) Sm Alea aime 
1894] 4.4/3 5}0.9/2.0 4.3) 3.8) 1.0) 1.5)10.4) 4.5] 5.9] 7.2) 9.0) 6.9 2.1| 2.4| 7.9/6.4/1.5) 2.7) 6.3°3 & 2.5/3.4/3.8]1.9/1.9)2.1 
1895] 3.8/2.8]1 0/1.0] 7.5) 2.9) 4.6] 4.6] 7.6] 5.0) 2.6] 2.9] 6.2] 4.6] 1.6] 3.1] 4.4°2.7]1.7| 2.1] 2.7]9.9 1.8 2.7/5.411.5 3.9/7.3 
1896 12.6|8.1 4.5/4.6] 9.9) 8.0) 1.9] 3.9)10.2) 7.9] 2.3} 2.6) 7.8} 6.9) 0.9) 1.6) 8.3 5.0/3.4) 5.6] 8.5/5.3 3.2/3.4]7.3/2.5 4.8/7.8 
1897/12.9/4.5/8.4/9.3|11.8) 10.4) 1.4) 3.1)16.0/11.8) 4.2) 4.8)15.8/11.3 4.5) 4.6)11.2 7.0}4.2) 4.3) 6.9]4.0 2.9'6.3)7.5/4.4 3.1/5.2 
1898} 7.2 3.2}4.0/6.0 11.4) 7.0| 4.4] 5.2)17.7/10.8) 6.9] 7.8/18.0/11.4| 6.6) 6.8/13.5 9.7/4.1] 6.0) 13.6]9.6 4.0/4.0/9.4/2.5 6.9/7.4 
1899] 8.9 6.5}2.4/3.6!10.2 5.5) 4.71 6.4114.0/10.9} 3.1! 6.0'12.8| 9.2! 3.6] 4.8! 9.8 7.0/2.8 5.1) 9.3]4.6 4.7 5.5 5,013.9 1.1/4.4 
August September October November December Extremes Totals 
~ v + j e 2 ~ 
=] | | =) =| a 
SlelolelalelolaleielelElBileleola|eizielel @ | z 
wf[S{e} si sles [Sl el sisi hls eis) s/s; e] s/h) 2) 2) gs] & | eg 
S(PEla Si Piel a si Pi eials|Blelelsi Pls ais) »| 6] & | & 
Rl |Ale SIP IAIMIS le /Ale ae Ale le] alae l/al we | Al ae! 
1894] 2.9 | 1.5) 1.4 2.6] 5.8 3.0 2.8] 4.7] 4.7 | 2.7) 2.0] 3.1] 3.0 , 2.8] 0.2] 0.4 oe 0.8] 0.8) 10.4) 1.5 8.9 32.9 
1895] 4.3 | 1 8] 2.5] 3.5] 5.8 | 2.2] 3.6] 8.8] 2.6 | 1.2) 1.4] 2.7] 2.6! 1.9] 0.7] 1.6) 13.1 2.5]10.6]11.5} 13.1 | 0.9 | 12.2 | 51.9 
1896] 8.6 | 5.8} 2.8] 4.3] 5.6 | 4.0] 1.6] 3.7] 6.9 | 4.4) 2.5] 4.6) 6.5 | 5.0] 1.5) 1.9] 6.2]4.5) 1.7) 1.7) 12.6 | 2.5 | 10.1 | 45.7 
1897] 4.0 | 1.8] 2.2] 2.6} 2.1 | 1.7| 0.4] 0.6] 2 4} 1.9} 0.5) 0.6] 3.5 | 2.4) 1.1) 2.2) 3.5/3.0) 0.5) 1.2) 16.0] 1.7 | 14.3 | 44.8 
1898} 5.7 | 2.6] 3.1] 7.5} 5.1 | 3.5) 1.6] 6.2] 6.2 | 3.6) 2.6 3.9) 8.7 | 6.3] 2.4) 2.6] 8.2'5.8] 2.4] 3.8] 18.0] 2.5 | 15.5 | 67.2 
1899! 4.0 | 2.2] 1.8] 2.4! 3.6 | 2.2] 1.4] 26 3.5 2.6 0.9 1.1' 4.4 | 3.4] 1.0 1.6) 5.7/4.0) 1.7] 3.8! 14.0 | 2.2 118 7.3 
It is evident that the changes from year to year in the 
conditions of the river environment are such that they must 
be taken into consideration in any study of the fluctuations of 
the plankton. A glance at the general hydrograph (Pl. VIL.) 
shows that the years of our plankton work at Havana practi- 
cally include the extremes of conditions in the river; no two 
years present the same fluctuations, and both typical and aber- 
