BIOLOGICAL STUDY OF CHESAPEAKE BAY WATERS 
331 
taken frequently in the surface nets as well as in the bottom net, and the records show 
its occurrence as far north in the bay as area W, off Bloody Point. The records also 
show that this form was present in the bay during the cruises of July, August, October, 
1920, and January and March, 1921. A few other hydromedusa' were collected, 
some of which were identified provisionally. The complete list is as follows: Bou- 
gainvillia carolinensis McCrady, B. ramosa Van Beneden (provisional identification), 
Nemopsis bachei L. Agassiz, Blackjordia virginiana Mayer, Liriope scutigera McCrady 
(provisional identification), and Aglantha digitate Fabricius (too fragmentary to throw 
light on varietal relationships). 
SCYPHOMEDUS^E 
By far the most common jellyfish (or sea nettle, as it is called), in the region of 
Chesapeake Bay is Dactylometra quinquecirrha L. Agassiz. It occurs there usually 
in the "Chrysaora” stage, characteristic of the brackish water — that is, with 32 
marginal lappets and 24 tentacles and mature gonads instead of with 48 marginal 
lappets and 40 tentacles (R. P. Bigelow, 1890; Mayer, 1910). Mayer reports (p. 
588) that D. quinquecirrha in the 40-tentacle condition develops at the mouth of 
Chesapeake Bay "in the purer ocean water * * *” The unpublished observations 
of Radcliffe on cruises during October and December, 1915; January, March, April, 
June, July, August, and September, 1916, give a good idea of the seasonal abundance 
of older specimens of Dactylometra in the bay. During the October cruise this form 
was reported at practically every station from the mouth to Sandy Point, near Balti- 
more; on the December cruise it was seen very infrequently; during the cruises of 
January, March, April, and June it was not reported, although, of course, it may not 
have been entirely absent; on the July cruise it was very abundant, especially at the 
mouth of the bay and was found as far north as area X ; finally, during the September 
cruise it was still abundant at many stations. The records indicate that Dactylo- 
metra became abundant in the Chesapeake during July, 1916, and according to 
Radcliffe one fisherman, at least, in the southern part of the bay, anticipates a "run” 
during that time of the year and takes up his nets to prevent their "burning. ” Mid- 
summer and early fall apparently was the time of abundance of this form in Chesa- 
peake Bay during 1916, a conclusion which agrees with observations made along the 
New England Coast and at Tampa, Fla. Dactylometra in the "Chrysaora” stage 
has been found in considerable numbers by the writer in the Severn and Magothy 
Rivers during October, and Mayer reports it from St. Marys River, Md., early in 
November, 1904 and 1905. E. A. Andrews has found it in the fall, 10 miles up the 
Severn River and about the docks in Baltimore Harbor. Undoubtedly it is the com- 
mon form during the fall in the rivers emptying into Chesapeake Bay. Dactylometra 
quinquecirrha , according to the observations of H. B. Bigelow for the New England 
region, is strictly a coastal form and does not occur north of the Cape Cod region. 
In its "Chrysaora” stage it is able to survive through a large range of salinities, 
judging from observations made in the Chesapeake; but its geographical distribution 
indicates that it is a warm -water form. 
It is not improbable that Dactylometra breeds in Chesapeake Bay and that the 
planulse, scyphostomse, and ephyrse are present in the summer, winter, and spring, 
respectively, but the records on which the above discussion is based deal only with 
the older and easily seen specimens. However, the ephyrse of Dactylometra quinque- 
cirrha have been seen by W. K. Brooks at Fort Wool, in the southern part of the 
bay, and figures made from them have been published by Maj^er (1910). 
