155 
Putses oF ANUR#A HYPELASMA. 
| 
First record Pulses 
Year 
Date | Temp. Date | Temp.| No. 
ISD SSS, TES ey ee ae Jane2%1 80° | June27 |» 80° - | 1,200 
AL eT lcs e's June 28] 75° July 14 | 79° 10,400 
TSO Cmte ee esa Ae iS atte) Ae lays tos June 14 83° June 21 if en A010) 
Pulses Last record 
Year = 
Date Temp. No. Date Temp. No. Date | Temp. 
1896 | Aug. 15 Sm GO) en Sept 30)! — Sse 
oe AS) 74° | 3,600 
1897 Aug. 31 S0°"2)| 20,000" | Oct” +5 WAS 23,200 | Nov. 2 De 
1898 Aug. 16 “i> '16,,000 | sept..27 ioe 43,200 | Nov. 1 45° 
August pulse 15,200 eggs were found on the rise to 4,000 on the 
decline. 
The location.of the pulses of A. hypelasma is of special interest. 
It will be seen in Table I. that they occur in 1898 in the same col- 
lections in which the pulses of the other species of Anurea and many 
other rotifers occur, or in collections but a week removed. They 
coincide in general with dates of the ploiman maxima noted in the 
opening discussion, and exhibit the same correlation with hydro- 
graphic conditions and intercalation with the pulses of chlorophyll- 
bearing organisms which were noted in the general discussion and 
have been found in preceding species. The comparison with Anurea 
of the cochlearis group affords a curious instance of an entire sup- 
pression (Table I.) of one species of a genus (cochlearis) in the month 
of August and the occurrence of a normal pulse in ‘another (hypelas- 
ma). Comparison of the distribution of cochlearis in previous 
summers would lead us to expect a cochlearis pulse in August, 1898, 
