220 



Bactilariacea, and Chlorophycecs in the period in question in 1898 

 are (PI. II.) July 19, August 9, August 30, and September 27. The 

 apices of the Pedalion pulses are July 26, August 16, and September 

 27, the last coinciding with the pulse of chlorophyll-bearing organ- 

 isms. In 1897, the intercalation of the two pulses is apparent, and 

 in 1896, two out of three pulses are intercalated and a third is 

 coincident. As will be seen in Table I., these pulses of 1898 are 

 approximately coincident in many cases with those of other roti- 

 fers Synchceta, Polyarthra, Triarthra, and Brachionus. The sig- 

 nificance of this intercalation lies probably in the food relations of 

 the two groups of organisms. 



Females with a single egg attached to the body have been noted 

 at the times of the maxima of the pulses, or immediately thereafter, 



