CTEXOPHORES IX NEW JERSEY COASTAL WATERS. 99 



narrow outlets. Although these harbors had been frozen over 

 from the 5th of the month until about a week before my visit, 

 the quietness and depth of the water had apparently provided 

 conditions more favorable to survival of the ctenophores than 

 obtained in the open bay. In horizontal hauls of 8 meters each 

 with a net I meter square, as high as 19 Mnemiopsis were procured 

 per haul. Of these approximately 90 per cent, were in the 

 Pleurobrachia and Bolinopsis stages and must have come from 

 eggs liberated -ince the cold weather early in the month. 



No further visits were made to the region until March. MIICC 

 harbor- and much of the bay were ice bound from late 

 J. <iniary until the close of February. On March 8, 1924. water 

 tt mperature, 3.5 C., no Mnemiopsis were found. The. adverse 

 condition- resulting from the heavy freezing had evidently 

 elr- the few survivors in the harbors where they \\ere found 



on January i<)th. The disappearance of Mnemio/^ix from Little 

 1.^1 larbor in November and from the open waters of Barnegat 

 Bay early in January' is believed to be due chiefly to the effects 

 of hea\ y -tornis which raise much sand and debris from the 

 bottom. 



III. 



Tin. 1'i.iiAViOR OF Mnemiopsis AT Low TEMPI K \ HMKS. 



Parker '05 found \vhile working with M. leidyi during the 

 Mimmcr at Woods Hole, that partial cessation of the paddle 

 l>l.r urred by chilling to 8.5 C., with complete loss of 



movement at 5 C. The absence of movement at this tempera- 

 ture \va> ;-hown to be due to causes other than the failure of 

 nervous transmission. If 5 C. represented the temperature 

 below which, in their natural environment, movement of the 

 paddle plates of Mncmiopsis ceased, the organisms would perish 

 U-fore late autumn in New Jersey. The temperature of 5 C. as 

 determined by Parker must represent a minimum only for 

 Mncmiopsis adjusted to summer temperatures. 



At .-uiiM-t November 9 with the water temperature of Barnegat 

 Hay at 7.5 ("., large numbers of Mnemiopsis of all sizes were 

 found wherever sought. The following night was cold with a 

 >harp north wind. At 8 :3O the next morning numerous Mnemi- 

 were seen swimming actively at the surface near the 



