185) 
Putses oF ANUR4ZA HYPELASMA. 















9 First record Pulses 
Year 
Date Temp. Date emp, | No: 
TIDE, i sash ae ee eee June27:|) 280° June 27 B0° "|| 4;,200 
ODF cin Ae Re a Pe eee June 28) 75° July 14 92 10, 400 
| | 
LBOS sa 55 SAsegto cenit aire ieee June 14 83° June 21 lie T9600 
Pulses Last record 
Mear 
Date Temp. No. Date | Temp: No. Date | Temp. 
1896 | Aug. 15 PS Oey | | Seo Ol ee 
oe DBS) 74° 3,600 
1897 Aug. 31 80° | 20000) |}Oct.~ 5 TS 23,200 | Nov. 2 SD 
1898 | Aug. 16 77° | 16,000 | Sept. 27] 73° | 43,200 | Nov. 1 45° 
Octo 1s ony 13,500 








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 (cochlearts) in the month 
of August and the occurrence of a normal pulse in another (ypelas- 
ma). Comparison of the distribution of cochlearis in previous 
summers would lead us to expect a cochlearis pulse in August, 1898, 
