94 THURLOW C. NELSON. 



Mayer ('12) lists Beroe ovata as abundant along the coast of the 

 United States as far north as Chesapeake Bay. Hargitt ('04) 

 found it common at Woods Hole in 1901, though seldom taken in 

 numbers. 



My own records cover only some of the estuaries on the New 

 Jersey coast and do not include the area of oceanic coastal water 

 investigated by Mayer and by Bigelow. During the six years of 

 my investigations Pleurobrachia has been found but twice, 

 Beroc ovata for short periods during three seasons, while Mnemi- 

 opsis has been observed daily for months at a time. 



Pleurobrachia brunnea was first found by me October II, 1920, 

 occurring in vast swarms at the surface of water 1-2 meters deep 

 at the mouth of the Mullica River, Great Bay (cf. F*ig. i). 

 Associated with it were numerous Mnemiopsis leidyi and many 

 small medusae of several species. So numerous were the Pleuro- 

 brachia that the water for yards around the boat w r as white as 

 though with foam. The ctenophores were found in greatest 

 abundance in the tidal slick which forms along the eastern end of 

 the old Graveling natural oyster bed at the mouth of the Mullica 

 River. The first observation of them was at n :i5 A.M., 

 with bright sunlight, very light NW. wind, tide one third ebb, 

 water temperature 16.6 C., specific gravity i.oi82. 2 The 

 majority of the jellyfish were so close to the surface that they 

 could be dipped up in a fingerbowl for examination. 



During the afternoon of the same day large numbers of 

 Pleurobrachia were foand over much of Great Bay, and on 

 October i.5th, 6 Pleurobrachia and 3 Mnemiopsis were taken in 3 

 minutes towing with a 15-in. net in Little Egg Harbor. On my 

 next visit to the region, three weeks later (November 3 and 4), no 

 Pleurobrachia were found in Great Bay or in Little Egg Harbor. 

 Numerous Mnemiopsis were obtained in the former region; the 

 temperature was 13 C., specific gravity 1.0234. 



Occasional visits have been made during the autumn in 

 subsequent years but no Pleurobrachia have been found. From 



2 All figures for specific gravity are reduced to the basis of distilled water at 4 C. 

 Readings were made with an hydrometer calibrated by the U. S. Bureau of Stand- 

 ards and further checked in some instances by titration of standard sea wati r 

 obtained from the International Commission for the Investigation of the Sea, 

 Copenhagen. For comparison I have with the aid of Knudsen's Tables trans] > 

 Bigelow's salinity figures to specific gravity readings. 



