HETEROGENY AND VARIATION IN SOME OF THE 

 COPEPODA OF LONG ISLAND. 



ESTHER F. BYRNES. 



In the spring of 1898, my attention was attracted to certain of 

 the Copepoda that occur in large numbers in the fresh-water 

 ponds in some of the outlying districts of Brooklyn. The 

 material, which contained many Cyclops, was collected soon after 

 the ice had disappeared from the surface of these shallow pools 

 and even at this early season most of the Cyclops were large and 

 carried eggs in all stages of development. 



I isolated individuals with eggs, and subsequently observed 

 numerous color-changes, which accompanied the rapid growth 

 and extrusion of eggs into the egg-sacs. A single instance will 

 suffice to show the rapidity of these changes, and the fertility of 

 the individuals. On the iQth of April, 1898, a Cyclops, carrying 

 dark blue eggs, was isolated. On the 2Oth dark bluish ova could 

 be seen through the transparent body-wall, making the body ap- 

 pear dark, while the dark eggs in the egg-sacs had developed into 

 embryos of a reddish tint. On the 22d the copepod carried dark 

 eggs again, and the body was again almost colorless, with a faint 

 streak on either side, still marking the position of the ovaries. 

 On the 23d it remained unchanged. On the 24th the body was 

 again dark but no eggs were attached. On the 25th the dark 

 eggs were carried in appended sacs and the body was again col- 

 orless. On the 26th the dark eggs became detached. On the 

 2 /th the body again appeared dark. There is no record in my 

 notes for the next two days, but when I again looked at the 

 copepod the body was colorless. While it carried no egg-sacs, 

 the ova must have been discharged since the last record on the 

 2/th instant. 



I attempted to identify the form, which agreed with C. parcns 

 (Herrick), in most of the points that are regarded as species- 

 characteristics but it differed from C. parcns in the number of 

 its antennal segments. 



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